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Biomedical subjects

L Frati

Publications and source records attributed to L Frati.

At least 91 records · Page 5Linked to original sources
PubMed1998

Advanced carcinoma of the pancreas: phase II study of combined chemotherapy, beta-interferon, and retinoids.

Because of the poor response of pancreatic cancer to conventional therapy, the authors performed a phase II pilot study to evaluate whether beta-interferon and retinoids, added to active chemotherapeutic agents, could increase response rate and survival in a group of patients who had metastatic disease. Twenty-three chemotherapy-naive patients were treated as follows: epirubicin, 60 mg/m2, and mitomycin C, 10 mg/m2, intravenously on day 1; folinic acid, 200 mg/m2, and 5-fluorouracil (5-FU), 370 mg/m2, intravenously for 5 consecutive days. beta-Interferon, 1 x 10(6) IU/m2, subcutaneously three times a week, and retinol palmitate, 50,000 IU orally twice a day, were given between chemotherapy cycles. Patients having responses and disease stabilization were maintained with the same dose of beta-interferon and retinol palmitate. Treatment was given every 4 weeks for four courses or until onset of progression. A median of three courses of chemotherapy was delivered to each patient. All patients were evaluable. Eight patients responded (35%) and 8 (35%) had stable disease. Median time to progression and survival for all patients were, respectively, 6.1 months and 11 months. Toxicity was severe: 60% of patients had hematologic toxicity, 40% had gastrointestinal toxicity, 13% had cardiac toxicity, and 1 patient had a hemolitic-uremic syndrome. The combination of chemotherapy, beta-interferon, and retinoids shows activity in metastatic pancreatic carcinoma. Toxicity was high but patients who had responses and disease stabilization had prolonged symptom palliation.

Adenocarcinoma↗
PubMed1998

The use of a cationic liposome formulation (DOTAP) mixed with a recombinant tumor-associated antigen to induce immune responses and protective immunity in mice.

The cationic liposome DOTAP is a well-known transfection reagent. It has been manufactured and approved for clinical use, is readily available, and can be easily used as an adjuvant. These characteristics prompted us to investigate the effectiveness of DOTAP as an adjuvant to induce immune responses and protective immunity in mice using baculovirus-derived carcinoembryonic antigen (bV-CEA) as a model antigen. Two routes of administration and a dose-response study of bV-CEA were used in BALB/c mice to define the magnitude of the immune response as well as the most effective route of immunization. The results demonstrate differences in antibody titers, immunoglobulin (Ig)G isotype, and T-cell responses between the intravenous (i.v.) or subcutaneous (s.c.) route of immunization. The titer of the anti-CEA antibodies induced by the s.c. immunization was greater than the response by i.v. immunization. The s.c. route enhanced the IgG2a/2b isotype, whereas i.v. immunization elicited primarily IgG1. T-cell proliferation responses and cytokine production paralleled the humoral response (i.e., production was higher in the s.c. immunized animals). No differences in immunological responses were seen using either 25 or 10 microg of bV-CEA three times. An amount of 25 microg of bV-CEA/DOTAP given by s.c. immunization was sufficient in protecting mice from the transplant of syngeneic tumor cells transduced with the human CEA gene. We conclude that the cationic liposome DOTAP may be a useful immunoadjuvant for active anti-tumor immunotherapy in future clinical trials. This study will help to define the most effective way to use such an adjuvant.

Animals↗
PubMed1998

Viral glycoproteins accumulate in newly formed annulate lamellae following infection of lymphoid cells by human herpesvirus 6.

Ultrastructural analysis of HSB-2 T-lymphoid cells and human cord blood mononuclear cells infected with human herpesvirus 6 revealed the presence, in the cell cytoplasm, of annulate lamellae (AL), which were absent in uninfected cells. Time course analysis of the appearance of AL following viral infection showed that no AL were visible within the first 72 h postinfection and that their formation correlated with the expression of the late viral glycoprotein gp116. The requirement of active viral replication for AL neoformation was further confirmed by experiments using inactivated virus or performed in presence of the viral DNA polymerase inhibitor phosphonoacetic acid. Both conventional electron microscopic examination and immunogold fracture labeling with anti-endoplasmic reticulum antibodies indicated a close relationship of AL with the endoplasmic reticulum and nuclear membranes. However, when the freeze-fractured cells were immunogold labeled with an anti-gp116 monoclonal antibody, AL membranes were densely labeled, whereas nuclear membranes and endoplasmic reticulum cisternae appeared virtually unlabeled, showing that viral envelope glycoproteins selectively accumulate in AL. In addition, gold labeling with Helix pomatia lectin and wheat germ agglutinin indicated that AL cisternae, similar to cis-Golgi membranes, contain intermediate, but not terminal, forms of glycoconjugates. Taken together, these results suggest that in this cell-virus system, AL function as a viral glycoprotein storage compartment and as a putative site of O-glycosylation.

Cell Line↗
PubMed1998

Receptor-mediated endocytosis of keratinocyte growth factor.

Keratinocyte growth factor (KGF) is a fibroblast growth factor which acts specifically on epithelial cells, regulating their proliferation and differentiation. KGF elicits its activity through binding to and activation of KGF receptor, a splicing transcript variant of fibroblast growth factor receptor 2 (FGFR2). Here we analyzed the pathway of internalization of KGF and its receptor using several approaches, including the utilization in immunofluorescence and in immunoelectron microscopy of a functional KGF-HFc chimeric protein as a specific tool to follow the endocytosis of the growth factor and of its receptor. Western blot analysis with anti-FGFR2 and anti-phosphotyrosine antibodies, as well as parallel double immunofluorescence and confocal analysis of NIH3T3 KGFR transfectants treated with KGF at 4 degrees C, followed by incubations at 37 degrees C for different time points, showed that KGF induced endocytosis of tyrosine activated KGFRs. The use of KGF-HFc in immunofluorescence and in immunogold electron microscopy on KGFR transfectants, A253 epithelial tumor cells and human cultured keratinocytes allowed us to follow the early steps of KGF internalization and revealed that this process occurred through clathrin-coated pits. A quantitative ELISA assay confirmed that KGF-HFc binding on the cell surface rapidly decreased because of internalization. Our results demonstrate that KGF is internalized by receptor-mediated endocytosis and illustrate the involvement of clathrin-coated pits in this process.

3T3 Cells↗
PubMed1998

Epidermal growth factor binding sites in human pituitary macroadenomas.

The number of epidermal growth factor (EGF) binding sites was determined by competitive binding assays in a series of 46 pituitary macroadenomas. A single concentration of 125I-EGF (1 nM) was used for all experiments. In four cases, a displacement curve was obtained by adding increasing concentrations of cold EGF, and Scatchard analysis showed the presence of two classes of EGF binding sites, with Kd1 = 0.62 +/- 0.23 nM and Kd2 = 53.8 +/- 8.2 nM for the high- and low-affinity binding sites respectively. The distribution of EGF binding sites was studied in 42 cases by a single-point assay, in the presence and in the absence of a 100-fold cold EGF excess. A non-parametric distribution of EGF binding sites was observed (median 10.2 fmol/mg membrane protein, range 0.0-332.0). EGF-receptor positivity, defined as EGF binding > or = 10.0 fmol/mg protein, was observed in 23 samples (54.8%), especially in prolactinomas (76.5%, P < 0.05 vs other tumors taken together) and in gonadotrope adenomas (62.5%). EGF binding was higher in invasive than in non-invasive adenomas (median: 12.8 vs 0.0 fmol/mg membrane protein, P = 0.047), and especially in adenomas invading the sphenoid sinus (median 26.7 fmol/mg membrane protein, P = 0.008 vs other adenomas). EGF binding also tended to increase with the grade of supra/extrasellar extension according to Wilson (P = 0.15). Sex steroid receptors (SSRs) were simultaneously determined in both cytosolic and nuclear fractions of 31 pituitary adenomas. Estrogen and progesterone receptors were determined by an enzyme-linked immunoassay and androgen receptors by a competitive binding assay with [3H]methyltrienolone. No correlation could be found between EGF binding and either the gender and gonadal status of the patients, or the expression of SSRs by the adenomas. We conclude that the EGF family of growth factors may play a role in the evolution of a significant subset of human pituitary adenomas, especially in their invasiveness, and that a high EGF binding capacity may represent an additional marker of aggressiveness for these tumors. Sex steroids do not appear to have a significant role in the regulation of EGF binding in vivo in these tumors.

Adenoma↗
PubMed1998

Origin and gender determination of dried blood on a statue of the Virgin Mary.

In Italy, blood exudation from objects of worship recurs frequently in ancient chronicles and literature, in popular beliefs, and even in modern mass-media reports. This phenomenon, that was associated with epochal or catastrophic events, has roots that reach classical antiquity. In the last few years, several events connected with the detection of bloody "tears" on statues of the Virgin Mary required forensic medicine investigations. In the present report we describe genetic investigations conducted on dried blood of unknown derivation found on a statuette representing the Virgin Mary. To test the human or animal origin of the blood, we amplified Alu-specific sequences from DNAs obtained from the unknown sample and from humans, large apes, various Old and New World monkeys, a prosimian, mouse, common domestic artiodactyls and chicken. This investigation restricted the range of possible origin of the statue blood to humans, apes and Old World monkeys. To test the male or female origin of the blood, we used a multiplex nested polymerase chain reaction method, that allows the simultaneous amplification of the X-specific locus DXZ4 and of the Y-specific locus SRY. Considering the unlikelihood of an origin from simian Old World primates, the exclusive amplification of the X-specific product from the unknown sample and from human female blood controls, compared to the amplification of distinct X- and Y-specific bands from human male blood controls, strongly supports a human female origin of the statue blood.

Animals↗
PubMed1998

Upregulation of Epstein-Barr virus-encoded latent membrane protein by human herpesvirus 6 superinfection of EBV-carrying Burkitt lymphoma cells.

The effect of HHV-6 strain A infection on the expression of Epstein-Barr virus- (EBV-) encoded growth transformation-associated genes in two EBV-positive Burkitt lymphoma cell lines, Akata and P3HR-3, was investigated. The results indicate that HHV-6A upregulates the expression of the latent membrane protein LMP-1 in both cell lines. Expression of EBNA-2 was also upregulated in Akata cells following HHV-6A infection. Transfection of reporter constructs carrying the LMP-1 regulatory sequences (LRS; -634/+40) or its 5' deleted derivatives in Akata and in a T-lymphoblastoid cell line, J-Jhan, confirmed the presence of positive and negative regulatory elements responsive to HHV-6A infection in LMP-1 regulatory sequence (LRS). The majority of LRS constructs were under the influence of dominant negative factors. HHV-6A was able to override the effect of such factors acting on reporter plasmids containing the -634/-54, -324/-54, -214/-54, and -106/-54 parts of LRS. The plasmid that carried only the -54/+40 LRS region was constitutively active in both Akata and J-Jhan cells; in Akata, its activity was influenced by HHV-6A. The finding that HHV-6A infection may activate LMP-1 and EBNA-2 expression, which is essential for the immortalization of B-lymphocytes by EBV, shows a novel aspect of the interaction between these two herpesviruses.

Antibodies, Monoclonal↗
PubMed1997

Proline-rich tyrosine kinase-2 activation by beta 1 integrin fibronectin receptor cross-linking and association with paxillin in human natural killer cells.

Recent evidence indicates that integrin ligation results in activation of focal adhesion kinase (pp125FAK), the prototype of a new subfamily of nonreceptor protein tyrosine kinase (PTK), including FAKB and the proline-rich tyrosine kinase 2 (PYK-2), also termed cell adhesion kinase-beta or related adhesion focal tyrosine kinase. We have previously shown that cross-linking of alpha 4 beta 1 and alpha 5 beta 1 fibronectin receptors on human NK cells stimulates tyrosine phosphorylation of two proteins migrating at 105 and 115 kDa. Here we report that cross-linking of beta 1 integrins on human NK cells stimulates tyrosine phosphorylation and PTK activity of PYK-2. PYK-2 tyrosine phosphorylation was maximal at 1 min and started to decline 20 min after stimulation. Engagement of alpha 4 beta 1 and alpha 5 beta 1 either with specific mAbs or after cell adhesion to fibronectin or its 120- and 40-kDa fragments also triggered PYK-2 tyrosine phosphorylation. Stimulation of PYK-2 tyrosine phosphorylation was inhibited by the tyrosine kinase inhibitor herbimycin A, but not by EGTA, indicating that PYK-2 tyrosine phosphorylation is PTK, but not calcium, dependent. We also demonstrate that PYK-2 is constitutively associated with paxillin, which undergoes tyrosine phosphorylation with the same kinetics of PYK-2 upon beta 1 integrin ligation.

Animals↗
PubMed1997

Selective binding of shc-SH2 domain to tyrosine-phosphorylated zeta but not gamma-chain upon CD16 ligation on human NK cells.

Fc gamma RIII (CD16) is a hetero-oligomeric receptor composed of a ligand-binding alpha subunit associated with homo- or heterodimers of the TCR zeta- and Fc epsilon RI gamma-chains. We have previously demonstrated that CD16 ligation promotes complex formation between tyrosine-phosphorylated shc and Grb2, leading to activation of ras signaling pathway in human NK cells. Here we report that CD16 engagement induces rapid shc association with the tyrosine-phosphorylated receptor complex in human NK cells. In vitro binding studies demonstrate that this interaction is mediated by the shc-SH2 domain, and immunodepletion experiments indicate that the zeta- but not the gamma-chain has the capability to mediate this association. Jurkat cell clones expressing CD16-zeta or -gamma homodimers have been used to gain more information about the mechanism of shc/CD16 association. Our data show that, while engagement of both receptors induces tyrosine phosphorylation of shc and Grb2 recruitment, shc-SH2/receptor complex association is evident only in CD16-zeta but not in CD16-gamma transfectants. Overall, our data demonstrate that the adaptor protein shc can be recruited to the activated CD16 complex by interaction with tyrosine-phosphorylated zeta-chain in a SH2-dependent manner. These results also provide further support to the notion that zeta- and gamma-chains might couple to different biochemical pathways.

Cells, Cultured↗
PubMed1997

CD16 cross-linking induces both secretory and extracellular signal-regulated kinase (ERK)-dependent cytosolic phospholipase A2 (PLA2) activity in human natural killer cells: involvement of ERK, but not PLA2, in CD16-triggered granule exocytosis.

The phospholipase A2 (PLA2) enzymes play a central role in diverse cellular processes including phospholipid digestion and metabolism, host defense, and cell signaling. We investigated the ability of CD16 clustering to trigger PLA2 and extracellular signal-regulated kinase (ERK) activation in human NK cells, as well as their possible involvement in CD16-stimulated degranulation. Both secretory (sPLA2) and cytosolic (cPLA2) PLA2 were rapidly activated upon CD16 cross-linking; sPLA2 was found in the supernatant and also in a cell-associated form. cPLA2 activation was controlled by the ERK pathway as indicated by the close correlation between their kinetics of activation and by the ability of the specific MEK inhibitor, PD 098059, to abolish cPLA2 activation. CD16 stimulation also resulted in the generation of platelet-activating factor (PAF) and leukotrienes; both phospholipases contributed to their biosynthesis. Using the pharmacologic inhibitors AACOCF3, p-bromophenacyl bromide (pBPB), and PD 098059, which specifically inhibit cPLA2, sPLA2, and MEK, respectively, we demonstrated that the ERK signaling pathway, but not cytosolic or secretory PLA2, is required for CD16-triggered granule release.

Antibodies, Monoclonal↗
PubMed1997

Transcription of latent and replicative Epstein-Barr-virus genes in bone-marrow and peripheral-blood mononuclear cells of healthy donors.

Reverse-transcriptase polymerase chain reaction has been used to analyze the expression of 2 latent genes (EBNA-1 and LMP-1) and one replicative gene (BZLF-1) of Epstein-Barr virus in mononuclear cells from bone marrow and peripheral blood of healthy donors. EBV-gene transcription was detected in 8 out of 15 bone-marrow samples. Among these, 5 allowed the detection of latency-associated transcripts in the absence of BZLF-1 expression. Only one sample showed positivity for expression of both latent and lytic genes. In 2 cases, BZLF-1 was the only transcript detected. In peripheral blood, 4 out of 7 samples showed evidence of EBNA-1 transcription; LMP-1 was expressed in 5 samples, and in 2 cases concomitant expression of EBNA-1 and BZLF-1 was detected. These results provide a direct demonstration by RT-PCR of EBV-gene transcription in bone-marrow-resident viral infected cells and suggest, in contrast to previous studies on peripheral blood, that LMP-1 and BZLF-1 are frequently transcribed also in absence of EBV-related disease. The heterogeneous viral gene expression found makes it difficult to define a pattern of viral latency in vivo which coincides with that described for lymphoblastoid or Burkitt's-lymphoma cell lines at different stages of differentiation.

Animals↗
PubMed1997

2-Aminopurine unravels a role for pRB in the regulation of gene expression by transforming growth factor beta.

Transforming growth factor type beta (TGFbeta) is a pleiotropic factor that regulates different cellular activities including cell growth, differentiation, and extracellular matrix deposition. All the known effects of TGFbeta appear to be mediated by its interaction with cell surface receptors that possess a serine/threonine kinase activity. However, the intracellular signals that follow receptor activation and lead to the different cellular responses to TGFbeta are still largely unknown. On the basis of the different sensitivity to the protein kinase inhibitor 2-aminopurine and the phosphatase inhibitor okadaic acid, we identified two distinct pathways through which TGFbeta activates a genomic response. Consistently, 2-aminopurine prevented and okadaic acid potentiated the induction of JE by TGFbeta. The induction of PAI-1 and junB was instead potentiated by 2-aminopurine, after a transient inhibition and was unaffected by okadaic acid. The superinducing effect of 2-aminopurine required the presence of a functional RB protein since it was abolished in SV40 large T antigen-transfected cells, absent in the BT549 and Saos-2 RB-defective cell lines, and restored in BT549 and Saos-2 cells after reintroduction of pRB. The effects of 2-aminopurine on the TGFbeta inducible junB expression occur in all the cell lines examined suggesting that junB, and possibly other genes, can be regulated by TGFbeta through a distinct pRB-dependent pathway.

2-Aminopurine↗
PubMed1997

Neuramide inhibits Epstein-Barr virus-induced transformation activity and proliferation of transformed B lymphocytes.

Neuramide, in Italy, is a prescription drug and contains various polypeptides, with molecular weights ranging between 10,000 and 1,000. It is commonly used in Italy for the clinical therapy of varicella-zoster and other viral herpetic diseases. In the present study, we investigated its effect on the in vitro transformation activity and transformed status of the Epstein-Barr virus (EBV), ab herpesvirus closely associated with infectious mononucleosis (IM), nasopharyngeal carcinoma (NPC) and Burkitt's lymphoma (BL). Antiviral effects of neuramide were evaluated on viral-induced immortalization, transformed status and DNA synthesis. Our results show that simultaneous and/or post-treatment of EBV-infected lymphocytes with neuramide, at a concentration of 2 inhibiting units (IU)/ml, blocks EBV-mediated transformation and related events, whereas pretreatment does not show any inhibiting activity against EBV. Neuramide was also found to be a potent inhibitor of the proliferation of EBV-transformed B lymphocytes in vitro. These results suggest that the molecular mechanisms of action of the drug should be investigated more closely and also support the necessity to further purify the active polypeptides, in order to improve its possible in vivo efficacy in EBV-associated diseases, such as infectious mononucleosis and other lymphoproliferative diseases.

Antimicrobial Cationic Peptides↗
PubMed1997

Randomized trial of filgrastim vs. sequential filgrastim and molgramostim after dose-intensified carboplatin, cyclophosphamide, and etoposide: a phase I pilot study.

This phase I randomized study was designed in order to verify if the sequential administration of filgrastim, a granulocyte colony-stimulating factor (G-CSF), and molgramostim, a granulocyte-macrophage colony-stimulating factor (GM-CSF), was superior to filgrastim alone in improving tolerance of dose-intensified carboplatin (CBDCA), cyclophosphamide (CTX), and etoposide (VP-16). A group of 10 heavily pretreated patients with stage IV disease and no therapeutic option were enrolled into the study. They received two courses of the same chemotherapy with CTX and VP-16 at doses of 1,500 mg/m2 and 400 mg/m2, respectively. CBDCA doses were escalated from 450 to 600 mg/m2. After chemotherapy each patient was allocated randomly to receive either 14 days of G-CSF (arm A) or 7 days of G-CSF followed by 7 days of GM-CSF (arm B). Crossover in the second chemotherapy course was accomplished. Both G-CSF and GM-CSF were given 5 microg/kg/day, subcutaneously. Twenty chemotherapy courses are evaluable, 10 in each arm. Absolute neutrophil count < 1 x 10(3)/microl was observed for 54 days in arm A vs. 68 days in arm B (P < 0.02); platelet (PLT) count < 20 x 10(3)/microl, 57 days vs. 30 days (P < 0.01); days of hospitalization 35 vs. 16 (P < 0.38); PLT transfusion, 107 vs. 58 (P < 0.01); packed red blood cell unit transfusions, 15 vs. 5 (P < 0.13). Seven patients had responses. These data indicate that dose-intensified chemotherapy may be delivered without bone marrow or peripheral stem cell support, with acceptable toxicity, and that, while G-CSF alone shortens days of neutropenia, the combination of the two cytokines shortens the time of thrombocytopenia and decreases the number of PLT transfusions.

Adult↗
PubMed1997

Transcriptional regulation of intercellular adhesion molecule 1 by phorbol ester in human neuroblastoma cell line SK-N-SH involves jun- and fos-containing activator protein 1 site binding complex(es).

In this study, the regulatory elements involved in ICAM-1 transcriptional response to phorbol ester (12-0-tetradecanoylphorbol-13-acetate; TPA) have been investigated in the human neuroblastoma cell line, SK-N-SH. TPA induced intercellular adhesion molecule 1 (ICAM-1) protein expression in SK-N-SH cells within 24 h of treatment as judged by indirect immunofluorescence. Basal ICAM-1 mRNA levels were barely detectable in untreated SK-N-SH cells but were induced by TPA to a maximal level with 4 h and were reduced thereafter. Analysis of the 5' promoter sequence of ICAM-1 revealed two regions that functioned equally in the TPA induction of ICAM-1 transcription. The first region (-145 to -227) contained a nuclear factor-kappa B (NF kappa B) element. The second region (-316 to -390) contained a putative TPA-responsive element (TRE; TGATTCA) and a TATA box. Deletion and point mutation of the latter region indicated that the TRE was indeed the functional element within this region and acted fully and independently of all other elements including the TATA box at position -352. This TRE bound TPA induced specific nuclear complexes in vitro containing junD, c-jun, c-fos, and fra2 but not cAMP-responsive element binding/activating transcription factor family proteins. ICAM-TRE binding activity was induced within 30 min following TPA treatment. This preceded the appearance of ICAM-NF kappa B site binding activity. Cotransfection of c-jun and c-fos expression vectors into SK-N-SH cells induced transactivation from ICAM-1 promoter constructs containing the intact but not mutated TRE site. Primer extension analyses revealed that TPA had induced transcription exclusively at two sites -40 and -41 bp upstream of the translation start site. These data show that the ICAM-TRE and its cognate jun- and fos-containing transcription factors play a predominant role in the transcriptional response of ICAM-1 to the protein kinase C activator TPA in SK-N-SH cells.

Cyclic AMP Response Element-Binding Protein↗
PubMed1997

Modulation of keratinocyte growth factor receptor expression in human cultured keratinocytes.

Keratinocyte growth factor (KGF) belongs to the fibroblast growth factor (FGF) family, and its activity seems to be restricted to epithelial cells. It elicits its biological effects through binding to the KGF receptor (KGFR), a splicing transcript variant of FGF receptor 2 (FGFR2). The presence of multiple isoforms of FGFR2 and the overlapping specificities of the FGFs with respect to their receptors do not allow the use of anti-FGFR antibodies as specific immunocytochemical tools. Here we used a chimeric protein recently obtained by the fusion of KGF to the HFc portion of immunoglobulin G (La Rochelle et al., J. Cell Biol., 129: 357-366, 1995) to analyze the expression and distribution of KGFRs in human keratinocytes cultured in chemically defined medium and incubated with different Ca2+ concentrations to modulate their differentiation. We observed at both immunofluorescence and electron microscopic levels and by Western blot analysis of proliferation (K6) or differentiation (K1) markers that KGFR expression is up-modulated during keratinocyte differentiation. Cytofluorimetric and Western blot analysis revealed that exposure to the high Ca2+ differentiation signal resulted in a significant increase in KGFRs. RNase protection assay using a KGFR-specific cDNA probe demonstrated that this effect was correlated with a > 4-fold increase in KGFR transcript level. Our results suggest that the expression of KGFR, unlike that of the epidermal growth factor receptor, may control the proliferative-differentiative program from basal to suprabasal cells in human skin.

Antigens, Differentiation↗