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R W Stephens

Publications and source records attributed to R W Stephens.

At least 37 records · Page 2Linked to original sources
PubMed1999

Blast cell-surface and plasma soluble urokinase receptor in acute leukemia patients: relationship to classification and response to therapy.

Plasminogen activation in leukemia has been less well characterized than in other malignancies. However, the increased tendency to bleeding and tissue infiltration by leukemic cells are processes in which plasminogen activation may be involved. We have examined plasma and the peripheral blood mononuclear cell fraction from 80 patients including 53 patients with newly diagnosed acute leukemia and 27 patients with other hematological disorders as well as 21 healthy controls. In 28 of 29 examined patients with acute myeloid leukemia (AML) and in two of three patients with hybrid leukemia we found urokinase receptor (uPAR) on the cell surface, while most (7/9) samples from patients with acute lymphoblastic leukemia (ALL) were negative for uPAR. The plasma mean value for soluble uPAR (suPAR) was significantly elevated in patients with AML and ALL. In AML the highest values were found in patients who had residual disease after several cycles of chemotherapy. Compared to controls the uPA antigen levels in patient plasmas were elevated and decreased along with uPAR during treatment. Our results suggest that cell surface uPAR may be a useful marker for leukemia classification and in our material a high level of plasma suPAR correlated with resistance to chemotherapy in AML.

Acute Disease↗
PubMed1999

Presence of urokinase-type plasminogen activator receptor in urine of cancer patients and its possible clinical relevance.

High levels of urokinase-type plasminogen activator receptor (uPAR) are expressed in various types of cancer. Recent studies showed that cancer patients may have increased levels of soluble (s)uPAR in their serum. In the present study, we show that urine samples from healthy volunteers contain measurable amounts of suPAR. suPAR/creatinine levels from healthy controls showed only little variation over the day and were even stable during a month of continued monitoring. Importantly, urinary suPAR/creatinine levels were highly correlated with serum suPAR concentrations. Urinary suPAR levels were elevated in patients with different types of cancer. Interestingly, part of the urinary suPAR seemed to be present in a cleaved form, as has been found in tumor tissue extracts. Together with the recently established, cell migration-promoting effect of certain cleaved fragments of suPAR, the present data suggest that the measurement of urinary suPAR and/or its cleaved forms might have clinical implications.

Adult↗
PubMed1999

Determination of the complex between urokinase and its type-1 inhibitor in plasma from healthy donors and breast cancer patients.

BACKGROUND: The complex between urokinase (uPA) and its type-1 inhibitor (PAI-1) is formed exclusively from the active forms of these components; thus, the complex concentration in a biological sample may reflect the ongoing degree of plasminogen activation. Our aim was to establish an ELISA for specific quantification of the uPA:PAI-1 complex in plasma of healthy donors and breast cancer patients. METHODS: A kinetic sandwich format immunoassay was developed, validated, and applied to plasma from 19 advanced-stage breast cancer patients, 39 age-matched healthy women, and 31 men. RESULTS: The assay detection limit was <2 ng/L, and the detection of complex in plasma was validated using immunoabsorption, competition, and recovery tests. Eighteen cancer patients had a measurable complex concentration (median, 68 ng/L; range, <16 to 8700 ng/L), whereas for healthy females and males the median signal values were below the detection limit (median, <16 ng/L; range, <16 to 200 ng/L; P <0.0001). For patient plasma, a comparison with total uPA and PAI-1 showed that the complex represented a variable, minor fraction of the uPA and PAI-1 concentrations of each sample. CONCLUSION: The reported ELISA enables detection of the uPA:PAI-1 complex in blood and, therefore, the evaluation of the complex as a prognostic marker in cancer.

Aged↗
PubMed1998

The urokinase plasminogen activator system as a target for prognostic studies in breast cancer.

The identification of patients at high risk of relapse is currently one of the most important issues in breast cancer research. However, the selection of high-risk patients continues to be difficult due to the unpredictable course of this disease. Axillary lymph node status is currently recognized as the best clinical discriminant between good and poor prognosis, yet almost 30% of node-negative patients and 65% of node-positive patients will experience a relapse. Additional prognostic markers are therefore urgently needed. Since metastatic disease is the main cause of cancer patient morbidity and mortality, the measurement of molecules functionally involved in the regulation of tumor invasion and metastasis is attractive as a means to predict prognosis. Cancer invasion is a complex process in which degradation of the extracellular matrix plays a crucial role. This degradation is accomplished by the concerted action of several proteolytic enzyme systems, including generation of plasmin by the urokinase pathway of plasminogen activation, matrix metalloproteases, and other extracellular proteases. Increased expression and secretion of urokinase plasminogen activator (uPA) strongly correlates with the malignant phenotype of many types of cells, and the central role of uPA in tumor invasion is now well established. This review will focus on the prognostic impact of components of the urokinase plasminogen activation system in breast cancer with emphasize on methodological issues.

Breast Neoplasms↗
PubMed1998

Prognostic values of cathepsin B and carcinoembryonic antigen in sera of patients with colorectal cancer.

The level of cathepsin B (Cat B) was determined in sera obtained preoperatively from 325 patients with colorectal cancer using an ELISA. Control sera from 90 healthy blood donors were analyzed. The levels of Cat B detected included all forms that were present in the sera, i.e., mature enzyme, precursor molecule, and enzyme-inhibitor complexes. The level of Cat B was significantly increased in sera of patients with colorectal cancer. The median level was 10.7 ng/ml versus 2.1 ng/ml in controls (P < 0.0001). A correlation between Cat B serum level and advanced Dukes' stage (P < 0.003) was found, whereas no associations have been found with age, sex, or level of carcinoembryonic antigen (CEA). In survival analysis, the patients with high serum Cat B experienced significantly lower survival probability. At the optimal cutoff value of 9.4 ng/ml, the relative hazard ratio was 1.8 (95% confidence interval, 1.1-2.8; P = 0.016) in the univariate Cox proportional hazards model. The median observation time was 4.4 years (range, 3.2-5.5 years). In multivariate analysis, Dukes' stage was the strongest prognostic variable, followed by age, whereas serum Cat B and CEA were not significant prognostic factors in this model, in accordance with their association with Dukes' stage. When the data for Cat B and CEA were combined, CEA-positive patients were further separated by Cat B into high- and low-risk groups. Patients with high serum levels of both molecules had significantly shorter survival (relative hazard ratio of 2.2; 95% confidence interval, 1.5-3.2; P < 0.0001), as compared with patients with low levels of both molecules.

Adult↗
PubMed1997

The complex between urokinase plasminogen activator and its type-1 inhibitor in breast cancer extracts quantitated by ELISA.

ELISAs for urokinase plasminogen activator (uPA) and plasminogen activator inhibitor type-1 (PAI-1) have shown that tumor levels of these molecules are prognostic parameters in breast cancer as well as other types of cancer. These ELISAs measure the total amount of the given component, including preforms, active, inactive, and complex-bound forms. However, the amount of the active forms of a component may more closely reflect the ongoing level of proteolytic activity and thereby be particularly related to prognosis. Since the inactive complex between uPA and PAI-1 can only be formed the active forms of the individual components, we have developed a sensitive and specific uPA:PAI-1 complex ELISA consisting of a sandwich format with two monoclonal antibodies (MAbs) against PAI-1 as capture antibodies and three biotinylated MAbs against uPA as detector antibodies. The data were collected as kinetic measurements of bound alkaline phosphatase activity. A standard of uPA:PAI-1 complex could be specifically measured in the assay with a detection limit of 8 pg/ml and a linear relationship between signal and complex concentration up to 4 ng/ml. Neither free uPA nor free PAI-1 were detected by this assay and the addition to the internal standard of free PAI-1 in amounts up to 20 ng/ml or uPA did not reduce the detection of complex by the assay. This ELISA was applied to extracts from 20 individual breast cancers. Each tumor was extracted in two different buffers and the median concentration of uPA:PAI-1 complex in the optimal extraction buffer was 0.8 ng/mg protein, range 0.4-2.8 ng/mg protein. Extraction of the tumor tissue at a low pH prevented de novo formation of complex from free uPA and PAI-1 in the tissue without destabilizing preformed uPA:PAI-1 complex. During incubation of the assay plate at neutral pH further uPA:PAI-1 complex formation from free components in the extracts was blocked by p-nitrophenyl guanidinobenzoate (NPGB). Thus, the present assay selectively quantifies preformed complex in tumor extracts and will enable us, for the first time, to evaluate the potential prognostic value of the uPA:PAI-1 complex in cancer.

Animals↗
PubMed1997

A peptide sequence from the EGF-2 like domain of FVII inhibits TF-dependent FX activation.

We have found that synthetic peptides derived from the two epidermal growth factor-like domains of factor VII are inhibitors of tissue factor dependent factor X activation. Inhibition was most pronounced for a constrained sequence of amino acids corresponding to positions 91-102 of factor VII, Cys-Val-Asn-Glu-Asn-Gly-Gly-Cys-Glu-Gin-Tyr-Cys. The biological activity appeared to be localized to the tripeptide 'motif', Glu-Gln-Tyr, within the larger sequence. The cyclic peptide was also an inhibitor of tissue factor induced coagulation of plasma, using lipidated tissue factor or tissue factor expressed on the surface of living cells. However, it did not interfere with intrinsic coagulation. Inhibition of factor X activation was dose-dependent with an IC50 value of 350 microM. Kinetic analyses revealed non-competitive inhibition with respect to factor X and suggested that the peptide sequence interferes with the factor VII/tissue factor/factor X complex formation and function. A pentapeptide analog of the putative pharmacophore was also a dose-dependent inhibitor of factor X activation with an IC50 value of 560 microM, but the tripeptide, Glu-Gin-Tyr, alone was without effect. Our results suggest a direct role for the second epidermal growth factor-like domain of factor VII, and in particular its loop I, in the formation and function of the factor VII/tissue factor/factor X complex.

Amino Acid Sequence↗
PubMed1997

ELISA determination of soluble urokinase receptor in blood from healthy donors and cancer patients.

Measurement of urokinase receptor (uPAR) in tumor extracts has prognostic value, but assay of the soluble uPAR (suPAR) in peripheral blood may offer wider applications in cancer patient management. A tumor extract uPAR ELISA was modified to eliminate nonspecific plasma protein interference, enabling specific detection of suPAR in plasma and sera with >90% recovery of added calibrator. suPAR concentrations in citrate plasma correlated with sera in 93 healthy blood donors (r = 0.84, P <0.0001), with a median value for both of 1.2 microg/L. The plasma median for 19 advanced breast cancer patients was 2.9 microg/L suPAR, and a similar increase was found for 10 advanced colon cancer patients, consistent with release of suPAR from tumors into blood. Repetitive monitoring of suPAR in cancer patients' blood may have value in assessment of prognosis and tumor recurrence.

Adult↗
PubMed1996

Characterisation of cell-surface procoagulant activities using a microcarrier model.

A novel model is described for characterisation of cell-surface procoagulant activities and their inhibitors. Microcarrier beads were used to present living cells to recalcified blood plasma in the stirred measuring wells of an electromagnetic coagulometer. By this means the procoagulant activity on the surface of the cells could be automatically determined as clotting time. Procoagulant activity was investigated on normal and transformed cells, and representing hemopoietic, endothelial, muscle and connective tissue phenotypes. The procoagulant activity on each cell type was characterised by the use of specifically immunodepleted plasmas and specific inhibitors, including monoclonal antibodies. The predominant cell surface trigger of coagulation found in this series was tissue factor, and only blood monocytes provided some evidence for direct activation of factor X independent of FVII. Human ECV304 transformed endothelial cells were more closely studied as representative of a cell type constitutively expressing procoagulant. Coagulation mediated by ECV304 cells was found to be strictly dependent on tissue factor, as shown by an inhibitory monoclonal antibody, and on coagulation factors V, VII and X. ECV304 procoagulant activity was strongly inhibited by active-site-inactivated FVIIa, a synthetic peptide inhibitor of FXa (Tenstop) and the thrombin inhibitor, hirudin. While not appropriate for routine clinical assessment of coagulation factor function, we have found this model to be valuable in characterising the procoagulant activity on different cell types and particularly useful as a drug discovery tool in the search for new anticoagulants.

Blood Coagulation↗
PubMed1996

Induction of monocyte tissue factor procoagulant activity during coronary artery bypass surgery is reduced with heparin-coated extracorporeal circuit.

The possible activation of monocytes to express tissue factor procoagulant activity (TF-PCA) during CPB (cardiopulmonary bypass) was investigated. 22 patients undergoing myocardial revascularization were randomly assigned to two groups. In group C, heparin-coated circuits (Duraflo II) and reduced systemic heparinization (ACT > 250s) were used. In group NC, non-coated circuits and standard heparin administration (ACT > 480s) were used. Adherent monocytes retrieved from the oxygenators immediately after bypass arrest showed a 2-3-fold increase in TF-PCA when compared to circulating cells pre-CPB (P < 0.01). When cell PCA was expressed as percent change from pre-CPB (baseline) values, circulating monocytes in group NC at CPB-arrest showed a 2-fold increase in PCA compared to group C (P < 0.05). Moreover, the percent increase in PCA of oxygenator-retrieved monocytes was 7-fold in group NC and 2-fold in group C (P < 0.008 and P < 0.004, respectively). Thus, heparin-coating of the extracorporeal circuit reduced induction of adherent cell TF-PCA by 70% (P < 0.05). Thus, monocyte TF-PCA may cause activation of the extrinsic coagulation pathway during CPB surgery. It is apparent that heparin-coating enhanced biocompatibility of extracorporeal circuits. Reduced systemic heparinization in group C proved to be safe. However, further reduction of heparin administration may not be advisable, since monocytes were still activated in the coated oxygenator.

Blood Coagulation↗
PubMed1995

Retinoic acid reduces induction of monocyte tissue factor and tissue factor/factor VIIa-dependent arterial thrombus formation.

Agents that downregulate the induction of monocyte/macrophage tissue factor (TF) activity may attenuate the thrombotic risk associated with mechanical restoration of vessel patency or artificial arterial grafting. In such events, procoagulant macrophages in the atherosclerotic plaque and procoagulant monocytes adherent to artificial materials may be exposed to the blood stream. Ishii et al (Blood 80:2556, 1992) reported that induction of endothelial TF is downregulated by all-trans retinoic acid (ATRA), and Conese et al (Thromb Haemost 66:662, 1991) reported that retinoids downregulate monocyte procoagulant activity (PCA). These findings led us to investigate the effect of ATRA on monocyte TF expression, and to study the effect of ATRA on monocyte-induced thrombus formation in a model system of human arterial thrombogenesis. Induction of PCA in human peripheral blood monocytes by 0.5 microgram/mL lipopolysaccharide (LPS) was dose dependently reduced by ATRA, reaching a reduction of 56% at 10(-5) mol/L ATRA (P < .0001). A 38% reduction (P < .0007) in LPS-induced TF antigen expression was observed at an ATRA concentration of 10(-6) mol/L. Adherence of monocytes to plastic cover slips (Thermanox, Miles Laboratories, Naperville, IL) also triggered induction of cellular PCA, which was inhibited by more than 80% by an anti-TF monoclonal antibody (MoAb) (P < .002). Inclusion of ATRA (10(-6) mol/L) reduced this PCA by 40% (P < .03), and the TF antigen expression by 30% (P < .0001). Exposure of Thermanox adherent monocytes to flowing nonanticoagulated human blood in a parallel-plate perfusion chamber device at an arterial wall shear rate of 650 s-1 elicited significant fibrin deposition and platelet thrombus formation. Partial interruption of this thrombus formation was achieved by 10(-6) mol/L ATRA, which reduced the fibrin deposition by 80% (P < .02) and platelet thrombus formation by 50% (P < .05). In comparison, incubation of adherent monocytes with the anti-TF MoAb before the blood exposure, reduced the fibrin deposition by 83% (P < .02) and platelet thrombus volume by 75% (P < .0008). Thus, ATRA is an effective down-regulator of monocyte TF-PCA, and may reduce thrombotic complications at sites of plaque rupture, at plaque disruption after percutaneous transluminal angioplasty procedures, or on surfaces introduced by artificial arterial grafting.

Blood Platelets↗
PubMed1994

Reduced thrombus formation in native blood of homozygous factor VII-deficient patients at high arterial wall shear rate.

Inhibition of thrombin formation in flowing native blood reduces thrombus formation on subendothelium, dacron, or collagen fibrils at arterial wall shear rates of 450 to 650 s-1. In the present study, we have investigated the role of low levels of factor VII (FVII) in thrombus formation on collagen fibrils at arterial wall shear rates of 650 s-1 (coronary arteries), 2,600 s-1 (mildly stenosed arteries), and 10,510 s-1 (severely stenosed arteries) in parallel-plate perfusion chambers. In the perfusion chamber with the highest wall shear rate, thrombus formation took place at the apex of an eccentric stenosis, which reduced the cross-sectional area of the blood flow channel by 80%, thus simulating thrombus formation at an atherosclerotic plaque rupture. Native blood from 21 healthy volunteers and 12 homozygous FVII-deficient patients was drawn by a pump directly from an antecubital vein over a surface of fibrillar collagen positioned in the respective perfusion chambers. The patients had FVII coagulant activities ranging from 1.3% to 4.5% and FVII antigen levels of 16% to 23% of normal. Immunoaffinity purification of the patients' FVII followed by electrophoresis (sodium dodecyl sulfate-polyacrylamide gel electrophoresis [SDS-PAGE]) and immunoblotting showed a protein with similar molecular mass as normal FVII. In the perfusion studies, a reduction in thrombus volume of 54% of normal (P < .007) at 10,510 s-1 was observed. The deposition of fibrin on the thrombogenic surface and the plasma level of fibrinopeptide A (FPA) in blood samples collected distal to the perfusion chamber were concomitantly reduced (P < .002 and P < .04, respectively). The plasma FPA level was also reduced at 2,600 s-1 (P < .04), but not at 650 s-1. However, at the lower shear conditions, the thrombus volume and the fibrin deposition were within the ranges observed in normal blood. The platelet-collagen adhesion was not affected at any of the three shear conditions. Thus, low plasma levels of FVII result in significantly less formation of thrombin and fibrin in and around growing platelet masses at high shear condition. This may weaken the thrombus stability and reduce platelet recruitment, thereby lowering thrombus volume. In support of this theory, one patient with afibrinogenemia had an 83% reduction in thrombus volume at this high shear condition.

Afibrinogenemia↗
PubMed1994

Tissue factor-induced coagulation triggers platelet thrombus formation as efficiently as fibrillar collagen at arterial blood flow conditions.

The relative importance of vessel wall tissue factor (TF) in initiating thrombogenesis is not well defined. In contrast, vessel wall collagens have been well documented as potent inducers of thrombus formation. We compared the potency of a human TF/phospholipid surface with that of a surface consisting of human type III collagen fibrils in triggering thrombus formation in native human blood at venous and arterial blood flow conditions. A commercial preparation, Thromborel S, was used as a source of human TF. Biochemical characterization of this preparation revealed small amounts of FVII, FIX, and FX proteins. Coagulant activity of these proteins was associated with the FVII protein only, although it was a very low activity. Studies with anti-TF antibodies in a one-stage clotting assay showed that the procoagulant activity of Thromborel was mainly a result of TF. The molar ratio of TF to phospholipid was 1:2 x 10(7). Thrombus formation in flowing nonanticoagulated human blood drawn directly from an antecubital vein was triggered by either Thromborel S or collagen fibrils coated on Thermanox coverslips in a parallel-plate perfusion chamber device. A 1:50 Thromborel S dilution gave maximal fibrin deposition (90% surface coverage) at a wall shear rate of 100 s-1. However, pretreatment of the TF surface with a monoclonal anti-TF antibody reduced this fibrin deposition by 93% (P < .001). Thus, TF was essential for the procoagulant activity of the Thromborel S surface in this flow system also. At higher wall shear rates (650 and 2600s-1), less fibrin was deposited, but the platelet thrombus formation on the fibrin mesh increased dramatically.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation↗
PubMed1993

Persistence of plasmin-mediated pro-urokinase activation on the surface of human monocytoid leukemia cells in vitro.

Human leukemia cell lines, unlike those from adherent tumors, have been shown to continuously activate the pro-urokinase (pro-u-PA) they produce. In the present study we found that, in normal cell-culture conditions in 10% FCS the plasminogen activation cascade works continuously on monocytoid leukemia cells, which expressed plasmin activity and active u-PA on their cell surface. This plasmin catalyzed the conversion of the produced pro-u-PA to active 2-chain urokinase (tcu-PA), and was derived from bovine serum plasminogen by the activity of cell-bound tcu-PA. Plasmin generation was abolished and pro-u-PA accumulated in cell cultures that were grown for several days, either in the presence of serum thoroughly depleted of plasminogen, or in the presence of 1 mM tranexamic acid. Plasmin generated on the cell surface was found to be present in 2 enzymatically active fragments, of M(r) 85,000 and M(r) 50,000, which were slowly released into the growth medium. These fragments could activate pro-u-PA in serum-free growth medium. Most of the bound plasmin could be washed off cells with 10 mM tranexamic acid, but complete removal of plasmin from the cell surface required washing of the cells with acid-glycine pH 3.0.

Animals↗
PubMed1993

Binding of tissue-type plasminogen activator to human melanoma cells.

We have shown (Bizik et al., Cell Regul 1:895-905, 1990) that tPA can activate plasminogen on the surface of human melanoma cells in the presence of alpha 2-macroglobulin (alpha 2M) secretion. In the present study, we investigated the binding of tPA on the surface of Bowes melanoma cells, selected since they lacked production of PAI-1 and alpha 2M. Elution of tPA from the cell layers indicated that polylysine (5 micrograms/ml) and tranexamic acid (10 mM), an analog of lysine, were the most efficient agents for disrupting the interaction between tPA and cell surface component(s). Using a panel of monoclonal antibodies against individual domains of tPA revealed that an antibody directed to the kringle-2 domain of tPA interfered most significantly with cell-surface plasmin generation. As tPA is a glycoprotein, interactions between the tPA sugar moieties and cell surface were also tested by the use of a series of monosaccharides. N-acetyl-D-glucosamine (100 mM) was the most potent sugar to release tPA from melanoma cells, but the results indicated that the oligosaccharides of tPA play only a supportive role in the binding of tPA to the cell surface. Quantitative comparison of the cell surface localized tPA, which was eluted by tranexamic acid, with the total cellular tPA showed that cell surface bound tPA could represent up to 10%. We conclude that tPA interacts with the melanoma cell surface in a similar manner as has been described for binding of tPA to fibrin and to the putative endothelial cell surface receptor.

Antibodies, Monoclonal↗
PubMed1993

Proteolytic activity in leg ulcer exudate.

Twenty-five leg ulcer exudate samples from 17 patients with chronic non-healing venous leg ulcer were analyzed for proteolytic activity using radial caseinolysis procedures and zymographic analysis, and for fibronectin fragmentation using immunoblotting technology. Caseinolytic activity was detected in 21 of the 25 samples. A minority of them were inhibited (3 were totally, 6 partially inhibited) by aprotinin, a serine proteinase inhibitor, suggesting that proteinase(s) other than plasmin were also responsible for the caseinolysis. In zymographic analysis, 23 of the 25 samples showed positive reactions for enzyme activities comigrating with plasmin and urokinase-type plasminogen activator. Fibronectin fragmentation, another sign of proteolytic activity, was seen in all but 2 ulcers. No correlation was seen between bacterial infection or inflammatory cells and the above parameters in the wound fluid. Acute wound fluid collected from the donor sites of patients undergoing split skin grafting was used as a control. In the control specimens no proteolytic activity was found during the days following operation. These results show that there is proteolytic activity in the chronic ulcer exudate and support the possibility that the proteolytic activity and consequent fibronectin fragmentation may be related to the retarded epithelization and ulcer healing.

Adult↗
PubMed1993

Distribution and lateral mobility of the urokinase-receptor complex at the cell surface.

Pro-urokinase (pro-uPA) and activated uPA are confined to focal adhesions and cell-cell contacts. We studied the distribution of the uPA receptor (uPAR) on human fibroblasts (HES) and rhabdomyosarcoma (RD) cells by immunofluorescence and immunoelectron microscopy. Two monoclonal antibodies (MAb) utilized were against uPAR: MAb R4, which reacts with occupied and unoccupied uPAR, was concentrated at focal adhesions; MAb R3 reacting with unoccupied receptor stained cell surfaces diffusely. MAb R4 stained cell-cell contacts, tips of microspikes, and co-localized with vinculin. Of the matrix and integrin components tested, alpha v beta 3 integrin was found at focal adhesions but more centrally than uPAR. Since uPAR is anchored to the plasma membrane through a GPI lipid, we studied its mobility by antibody-induced clustering. This revealed that unoccupied uPAR was relatively mobile; MAb R3 redistributed it to clusters. In contrast, uPAR R4 and uPA antibodies at the focal contact sites remained mostly within focal contacts. Addition of exogenous uPA resulted in loss of R3 staining and increase of uPA in focal adhesions. These results suggest that occupancy of the receptor with uPA is associated with localization to cell contact sites and restricted lateral mobility.

Antibodies, Monoclonal↗