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Biomedical subjects

C E Klein

Publications and source records attributed to C E Klein.

At least 19 recordsLinked to original sources
PubMed2001

Colorado family physicians' knowledge of hereditary breast cancer and related practice.

BACKGROUND: The objective of this study was to describe Colorado family physicians' (FPs') knowledge of hereditary breast cancer and related practice behaviors. METHOD: A survey was mailed to 400 practicing FPs randomly sampled from the board-certified members of the Colorado Academy of Family physicians. RESULTS: Overall, knowledge of hereditary breast cancer was inadequate. Less than half of the respondents knew that BRCA mutations account for 0-10% of all breast cancers; 38% knew the lifetime risk for non-carriers, and 17% responded that a known carrier would have a lifetime breast cancer risk of 50%. Just 45% knew that a BRCA1 mutation could pass from father to daughter. Similarly, only half reported an increased ovarian cancer risk for BRCA1 carriers, and an increased risk for male breast cancer for BRCA2 carriers. All respondents reported that taking a family cancer history was part of their regular clinical practices. The majority reported having referred no patient for cancer genetic counseling or testing within the prior year, with only two reporting having ordered BRCA1 or BRCA2 testing within the year. There was no significant sociodemographic or knowledge difference between the physicians who reported referring patients and the others (p > 0.05). There was interest in learning more about hereditary breast cancer, with rural physicians requesting Internet and teleconference courses. CONCLUSIONS: As cancer genetics emerges into the primary care arena. FPs recognize their knowledge deficit in this area. Future cancer genetic outreach for primary care providers statewide is necessary and would be welcomed, and may require a variety of educational and consultative approaches, depending on geographic location of practice.

Adult↗
PubMed2000

Basal-cell adhesion molecule (B-CAM) is induced in epithelial skin tumors and inflammatory epidermis, and is expressed at cell-cell and cell-substrate contact sites.

Basal-cell adhesion molecule (B-CAM) is a 90 kDa cell surface glycoprotein of the immunoglobulin superfamily that functions as a laminin-binding receptor. B-CAM is upregulated following malignant transformation of some cell types in vivo and in vitro, thus being a candidate molecule involved in tumor progression. As cutaneous distribution and function of B-CAM are largely unknown, we have studied its expression and regulation in normal and diseased human skin. In normal skin, B-CAM was expressed by endothelial cells of dermal blood vessels. In contrast, B-CAM was strongly upregulated within the tumor tissue of both malignant and benign epithelial skin tumors, including basal cell carcinomas, squamous cell carcinomas, keratoacanthomas, and common warts. Transformation-associated upregulation was confirmed in vitro, but normal keratinocytes also expressed B-CAM under culture conditions. Interestingly, the basal epidermal layer of normal-appearing skin surrounding the tumors also expressed B-CAM, and B-CAM were induced on the basal and apicolateral surfaces of basal keratinocytes in inflammatory skin disorders suggesting transformation-independent mechanisms of epidermal induction of the B-CAM. Immunoelectron microscopy studies of cultured transformed keratinocytes revealed that B-CAM was expressed at cell-cell and cell-substrate contact sites. Halting proliferation of transformed keratinocytes through cytostatic drugs resulted in decreased B-CAM synthesis. Likewise, inducing terminal differentiation in keratinocyte cultures by increasing the Ca(2+) concentration in the medium decreased B-CAM expression. In contrast, both ultraviolet A and B irradiation of cultured human keratinocytes resulted in significantly increased expression of the B-CAM. Overall, it appears that B-CAM expression in human skin is associated with activated states of keratinocytes, and that B-CAM may be involved in cell-cell adhesion or migration, in addition to its known function as a laminin receptor. J Invest Dermatol 115:1047-1053 2000

Carcinoma↗
PubMed2000

Phase I and pharmacokinetic study of irinotecan and docetaxel in patients with advanced solid tumors: preliminary evidence of clinical activity.

PURPOSE: The goals of this study were to determine the maximum-tolerated dose and describe the toxicities of the combination of irinotecan and docetaxel administered every 3 weeks to patients with advanced malignancies and, also, to evaluate the effect of irinotecan on the disposition of docetaxel and describe preliminary evidence of antitumor activity. PATIENTS AND METHODS: Eighteen patients received 85 courses (median, two courses; range, one to 15 courses) of treatment with irinotecan, administered over 90 minutes by intravenous infusion, followed by docetaxel, administered over 60 minutes by intravenous infusion. Four escalating dose levels of irinotecan/docetaxel (160/50 mg/m(2), 160/65 mg/m(2), 200/65 mg/m(2), and 200/75 mg/m(2)) were studied. Pharmacokinetic analyses were performed to evaluate the effect of irinotecan on the disposition of docetaxel. RESULTS: The most common and dose-limiting toxicity was myelosuppression, which consisted of neutropenia that was severe (National Cancer Institute common toxicity criteria [NCI CTC] grade 4) but brief (< 5 days) in 11 patients, with three episodes of febrile neutropenia. Nonhematologic toxicities of anorexia, nausea, and stomatitis were mild to moderate (NCI CTC grades 1 and 2), but there was one incidence each of both CTC grade 3 anorexia and nausea. All patients had total alopecia. Diarrhea was dose-dependent and severe in four patients who failed to take adequate antidiarrhea therapy. Five out of 16 assessable patients, one with cholangiocarcinoma, one with leiomyosarcoma, and three with non-small-cell lung cancer, achieved partial remissions. CONCLUSION: The combination of irinotecan and docetaxel causes significant reversible myelosuppression, which was dose limiting but led to no serious sequelae. There was no evidence of a clinically significant interaction using these two agents in this sequence. The combination showed antitumor activity at all the dose levels tested and should be further studied in a number of tumor types. The recommended phase II dose on this schedule is irinotecan 160 mg/m(2) and docetaxel 65 mg/m(2).

Adult↗
PubMed1999

Tissue inhibitor of matrix metalloproteinase-2 regulates matrix metalloproteinase-2 activation by modulation of membrane-type 1 matrix metalloproteinase activity in high and low invasive melanoma cell lines.

Activation of pro-matrix metalloproteinase (MMP)-2 on the surface of malignant cells by membrane-bound MT1-MMP is believed to play a critical role during tumor progression and metastasis. In this study we present evidence that MT1-MMP plays a key role for the in vitro invasiveness of malignant melanoma. Melanoma cell lines secreted latent MMP-2 when cultured on plastic. However, when cells were grown in floating type I collagen lattices, only high invasive melanoma cells activated proMMP-2. Activation could be inhibited by antibodies against MT1-MMP, by addition of recombinant tissue inhibitor of metalloproteinases (TIMP)-2 and by inhibition of MT1-MMP cleavage. MT1-MMP protein was detected as an inactive protein in all cell lines cultured as monolayers, whereas in collagen gels, active MT1-MMP protein was detected in the membranes of both high and low invasive melanoma cells. Production of TIMP-2 was about 10-fold higher in low invasive cells as compared with high invasive melanoma cells and was further increased in the low invasive cells upon contact to collagen. Thus, in melanoma cells TIMP-2 expression levels might regulate MT1-MMP-mediated activation of proMMP-2. High invasive melanoma cells displayed increased in vitro invasiveness, which was inhibited by TIMP-2. These data indicate the importance of these enzymes for the invasion processes and support a role for MT1-MMP as an activator of proMMP-2 in malignant melanoma.

Cell Movement↗
PubMed1999

Hypoxia-induced up-regulation of angiogenin in human malignant melanoma.

Angiogenesis is essential for tumor progression and metastasis, however, the angiogenesis regulators that are biologically relevant for human melanoma are still unknown. In this study, we analyzed the expression of the potent angiogenic factor angiogenin (ANG) in human melanoma in vitro and in vivo. Four different human melanoma cell lines and two normal melanocytes were kept either under normoxic or hypoxic conditions. After 24 h of hypoxic culture conditions, ANG was up-regulated in the melanoma cell lines but not in normal melanocytes. Induction levels correlated with the metastatic potential of the cell lines. These data were confirmed by Northern blot analysis. In contrast, induction of vascular endothelial growth factor by hypoxia was equally strong in the examined highly aggressive melanoma cell lines and in one nonaggressive cell line. Other angiogenic factors tested as well as the melanoma growth stimulatory activity (Gro-alpha) showed no up-regulation. Thus, in the present study, hypoxia-induced up-regulation in melanoma cells was only observed for ANG and vascular endothelial growth factor. Immunohistochemical studies showed that 8 of 10 melanomas and all 15 metastases were positive for ANG, particularly in the vicinity of small vessels, whereas all benign nevi were negative. Reverse transcription-PCR detected only weak ANG mRNA in nevi but strong signals in primary melanomas and metastases. In conclusion, we demonstrate for the first time enhanced expression of ANG in highly metastatic cell lines as well as in melanomas and metastases in vivo, suggesting that ANG expression is associated with the metastatic potential.

Angiogenesis Inducing Agents↗
PubMed1999

Functional hierarchy of simultaneously expressed adhesion receptors: integrin alpha2beta1 but not CD44 mediates MV3 melanoma cell migration and matrix reorganization within three-dimensional hyaluronan-containing collagen matrices.

Haptokinetic cell migration across surfaces is mediated by adhesion receptors including beta1 integrins and CD44 providing adhesion to extracellular matrix (ECM) ligands such as collagen and hyaluronan (HA), respectively. Little is known, however, about how such different receptor systems synergize for cell migration through three-dimensionally (3-D) interconnected ECM ligands. In highly motile human MV3 melanoma cells, both beta1 integrins and CD44 are abundantly expressed, support migration across collagen and HA, respectively, and are deposited upon migration, whereas only beta1 integrins but not CD44 redistribute to focal adhesions. In 3-D collagen lattices in the presence or absence of HA and cross-linking chondroitin sulfate, MV3 cell migration and associated functions such as polarization and matrix reorganization were blocked by anti-beta1 and anti-alpha2 integrin mAbs, whereas mAbs blocking CD44, alpha3, alpha5, alpha6, or alphav integrins showed no effect. With use of highly sensitive time-lapse videomicroscopy and computer-assisted cell tracking techniques, promigratory functions of CD44 were excluded. 1) Addition of HA did not increase the migratory cell population or its migration velocity, 2) blocking of the HA-binding Hermes-1 epitope did not affect migration, and 3) impaired migration after blocking or activation of beta1 integrins was not restored via CD44. Because alpha2beta1-mediated migration was neither synergized nor replaced by CD44-HA interactions, we conclude that the biophysical properties of 3-D multicomponent ECM impose more restricted molecular functions of adhesion receptors, thereby differing from haptokinetic migration across surfaces.

Antibodies, Monoclonal↗
PubMed1998

Human mast cells augment fibroblast proliferation by heterotypic cell-cell adhesion and action of IL-4.

Mast cells have been implicated in the pathogenesis of fibrosis because of their increased number in chronic inflammatory reactions. In a previous study, we had shown that human mast cells readily attach and form heterotypic cell-cell contacts when seeded on top of fibroblast monolayers. Here, we report that human mast cells stimulate fibroblast proliferation after cell-cell contact. Proliferation was measured by 5-bromo-2'-deoxyuridine or [3H]thymidine uptake of subconfluent fibroblast monolayers after attachment of mast cells that had been preincubated with mitomycin C. An 18-h coculture of the human mast cell line HMC-1 doubled proliferation of normal skin fibroblasts. Moreover, normal mast cells prepared from neonatal foreskin doubled fibroblast proliferation. The stimulatory effect was dependent on heterotypic cell-cell contact since it was not transferred by tissue culture supernatants from mast cells. We hypothesized that mast cell cytokines secreted after heterotypic cell-cell contact stimulate fibroblast proliferation. Several mast cell-derived cytokines were tested for effects on fibroblast proliferation. Only IL-4 was able to double fibroblast proliferation. Additional experiments revealed that: 1) the stimulatory effect of IL-4 as well as of the mast cell coculture could be completely abrogated by preincubation of fibroblasts with an anti-IL-4R mAb blocking ligand binding; 2) mast cell-derived IL-4 acts as a second signal for fibroblasts since it amplifies the action of low doses of obligatory fibroblast growth factors such as fibroblast growth factor or platelet-derived growth factor.

Cell Communication↗
PubMed1998

An antagonistic IL-4 mutant prevents type I allergy in the mouse: inhibition of the IL-4/IL-13 receptor system completely abrogates humoral immune response to allergen and development of allergic symptoms in vivo.

We have analyzed in vivo effects of the murine IL-4 mutant Q116D/Y119D (QY), which forms unproductive complexes with IL-4Ralpha and is an antagonist for IL-4 and IL-13 in vitro. Treatment of BALB/c mice with QY during immunization with OVA completely inhibited synthesis of OVA-specific IgE and IgG1. BALB/c-derived knockout mice lacking either IL-4 or IL-4Ralpha also did not develop specific IgE or IgG1, but mounted a much stronger IgG2a and IgG2b response than wild-type mice. In contrast, QY treatment of normal BALB/c mice suppressed specific IgG2a, IgG2b, and IgG3 synthesis, which may indicate the development of tolerance toward the allergen. Associated with the lack of IgE synthesis in QY-treated wild-type mice and in IL-4(-/-) mice used as a control was the failure to develop immediate cutaneous hypersensitivity or anaphylactic shock upon rechallenge. Interestingly, QY treatment also inhibited humoral immune responses and allergic reactivity in SJL/J mice, a strain that did not produce IgE, but displayed IgE-independent mast cell degranulation mediated by specific IgG1. We conclude that QY inhibits Ag-specific humoral immune responses and allergic symptoms mediated either by IgE or IgG1. It needs to be clarified how QY abrogates synthesis of IgG2a, IgG2b, and IgG3, but the induction of tolerance toward nonhazardous protein Ags should be advantageous for therapy of atopic disorders and other Th2-dominated diseases.

Allergens↗
PubMed1997

Migration of highly aggressive MV3 melanoma cells in 3-dimensional collagen lattices results in local matrix reorganization and shedding of alpha2 and beta1 integrins and CD44.

The three-step model of cell migration consisting of protrusion of a leading lamella, attachment to the substrate, and contraction of the cell body is well established for fibroblasts migrating across planar surfaces. However, it is not resolved to what extent the migration of cancer cells in a 3-dimensional tissue environment follows similar principles. Here, we present evidence that the migration of highly invasive MV3 melanoma cells in 3-dimensional collagen matrices follows the three-step concept of migration but also results in characteristic reorganization of the extracellular matrix. After incorporation in the lattice, MV3 cells spontaneously developed a slow type of migration (mean velocity, 0.19 microm/min), leading to alignment of collagen fibers at attachment sites, as detected from unfixed and fixed samples by confocal reflection contrast in combination with immunofluorescence staining. In the process of migration, the formation of focal clusters or stripes of alpha2 and beta1 integrins colocalized with binding sites to collagen fibrils at the leading as well as the trailing edge. In contrast, CD44 was nonclustered and redistributed toward the rear end of the cell. At detachment sites, dynamic fiber traction, localized fiber disruption, and the release of cell surface determinants, including alpha2beta1 integrins and CD44, resulted in circumscribed matrix reorganization. Not infrequently, these emerging tube-like paths of least resistance bordered by a dense fiber network facilitated the reorientation and contact guidance of proximate MV3 cells to migrate along the preexisting path. In conclusion, the migration of MV3 cells in 3-dimensional collagen lattices resulted in dynamic tissue reorganization and receptor shedding the consequences of which were directly visualized by combining confocal reflection imaging with immunofluorescence.

Animals↗
PubMed1997

Heterotypic cell-cell adhesion of human mast cells to fibroblasts.

Skin mast cells are typically located in the perivascular or perineural connective tissue. We observed that HMC-1 mast cells growing in suspension adhered efficiently to (> 90% of cells) and spread on top of fibroblast monolayers and to a lesser degree on purified extracellular matrix proteins. Since adhesive interactions determine cell migration and tissue localization we studied the mechanism. It was found that HMC-1 cells attach to collagen I and fibronectin, laminin, collagen IV and vitronectin, but not to collagens III and VI or hyaluronic acid. Adhesion to fibronectin, collagen I and laminin was completely inhibited by mAbs blocking beta 1-integrins, whereas adhesion of HMC-1 cells to vitronectin was inhibited by anti-alpha v-chain mAbs. However, attachment of HMC-1 cells to fibroblasts was not influenced by mAbs blocking beta 1- or alpha v-chain function, by RGD peptides or by mAbs interfering with other receptors, most notably c-kit. Identical results were obtained with normal mast cells isolated from human foreskin. These results indicate that human mast cells attach to fibroblasts independently of beta 1- or alpha v-integrins as well as of c-kit receptor-mediated mechanisms. The functional characteristics observed (i.e. only partial sensitivity to trypsin and EDTA, no increase in trypsin sensitivity by pretreatment with EDTA) suggest that cadherin receptors were not involved, and it is likely that the adhesion process observed involved not-yet-defined heterotypic cell-cell adhesion receptors.

Antibodies, Monoclonal↗
PubMed1996

Expression of the human alpha2 integrin subunit in mouse melanoma cells confers the ability to undergo collagen-directed adhesion, migration and matrix reorganization.

Previous studies have shown that cultured human and other mammalian cell require the alpha2 beta1 integrin receptor to reorganize and contract 3-dimensional extracellular matrix lattices containing collagen type I. This function is of prime importance for the later phases of wound healing, in which fibroblasts reorganize and contract extracellular matrix components newly deposited in the granulation tissue. It is also known that highly aggressive human melanoma cells have acquired this function, possibly enhancing their invasive potential. To further study alpha2 beta1-mediated functions, we expressed the human alpha2 and beta1 chains of integrins in mouse melanoma cells (BULT). The parental cell line was unable to exert known alpha2 beta1-mediated functions: The cells did not adhere, spread, or migrate on collagen type I, and they did not reorganize 3-dimensional collagen I lattices. Transfection of the human alpha2 chain was sufficient to confer not only specific adhesion to collagen type I in static adhesion assays, but also the ability to exert complex functions such as migration on collagen and efficient reorganization of collagen-I-containing matrices. Coexpression of the human beta1 chain did not further enhance these functions in BULT melanoma cells. This was underscored by the observation that alpha1-specific monoclonal antibodies were able to completely block the newly introduced functions, whereas beta1-specific antibodies had no such effect. Moreover, in transfectants expressing both the human alpha2 and beta1 chains, the human alpha2 chain did not preferentially associate with the human beta1 chain as compared with mouse beta-chains. This may indicate that the molecular structures guiding the physical association of the human alpha2 chain with beta chains are extremely highly conserved between the species.

Animals↗
PubMed1996

Decreased expression of alpha 2 beta 1 integrin in scleroderma fibroblasts.

Systemic scleroderma (SSc) is a complex connective tissue disorder of unknown etiology. In early stages of the disease, fibroblasts are activated to produce large amounts of collagen with subsequent fibrosis. Collagen metabolism of fibroblasts is modulated by their contact with the extracellular matrix (ECM), which involves distinct receptors on the cell surface, mainly belonging to the integrins. We investigated the expression of collagen receptor alpha 2 beta 1 in SSc and normal fibroblasts, since this receptor has been shown to be utilized by fibroblasts for adhesion to and reorganization of collagen I. 9 strains of scleroderma fibroblasts grown as monolayer cultures were first analyzed with respect to their collagen I expression. 6 of these strains were similar to controls "low" producers) and 3 strains showed up to 2-3 x higher levels of collage I mRNA expression ("high" producers). Northern hybridization using a cDNA probe specific for the alpha 2 integrin subunit revealed a decrease of the corresponding mRNA in SSc fibroblasts as compared to controls (75% versus 100%). "High" collagen producing cell strains displayed the lowest values for alpha 2 integrin mRNA. The decrease of alpha 2 integrin subunit expression at the mRNA level in selected fibroblasts was further substantiated by radioimmunoprecipitation using specific mAbs directed against alpha 2 integrin subunit. No significant changes in beta 1 integrin expression could be observed - neither at mRNA nor at the protein level. Our data indicate a correlation between excessive synthesis of collagen and low levels of alpha 2 integrin subunit expression in SSc fibroblasts. Further experiments should clarify whether this observation is a phenomenon specific for scleroderma or whether it reflects an "activated" state of fibroblasts.

Cells, Cultured↗
PubMed1996

Increased expression of a 38kd cell-surface glycoprotein MH99 (KS 1/4) in oral mucosal dysplasias.

A "window of expression" of a 38-kD cell-surface glycoprotein MH99 (KS 1/4 antigen) has been observed in dysplastic oral tissues using an MH99-specific monoclonal antibody. It appeared that expression of this epitope increases from baseline levels in normal oral epithelium to that of high levels in mild, moderate and severe dysplasia. In invasive squamous cell carcinoma, relatively low levels of expression were observed. In contrast, high levels of expression were demonstrated in basal cell carcinomas. Antibody reactivity could clearly distinguish between the margins of histologically normal and dysplastic tissues. It is envisaged that the expression of this cell-surface glycoprotein, which is possibly related to nidogen, a matrix-adhesion molecule with receptor-like function, could be used in monitoring progression or regression of these lesions and assessment of surgical excision margins. It could also be useful in in vivo and in vitro investigations into molecular changes underlying the formation of dysplastic lesions.

Antibodies, Monoclonal↗
PubMed1996

Migration of highly aggressive melanoma cells on hyaluronic acid is associated with functional changes, increased turnover and shedding of CD44 receptors.

Recent evidence indicates that CD44, a multifunctional adhesion receptor involved in cell-cell as well as in cell-matrix interactions, plays an important role in local progression and metastasis of malignant tumors. We have studied a set of human melanoma cell lines differing in their metastatic potential in nude mice as well as in normal melanocytes for changes in CD44 expression and function. All melanocytes and melanoma cell lines tested highly expressed the CD44 standard form (CD44s, 85 kDa) but variants at low levels only. With respect to one of the CD44-associated functions primarily involved in tumor progression we found that two highly metastatic tumor cell lines, MV3 and BLM, showed fivefold higher migration rates towards hyaluronate than melanomas with low metastatic potential and normal melanocytes. Moreover, the highly metastatic cell lines expressed four- to sixfold higher levels of the CD44 epitope involved in hyaluronic acid-binding (monoclonal antibody Hermes-1) than less aggressive melanomas and melanocytes. Hermes-1 efficiently blocked haptotaxis to hyaluronate, supporting the functional relevance of this epitope. In contrast, expression levels of other CD44s epitopes recognized by seven different anti-CD44 monoclonal antibodies were unchanged, suggesting that the migratory behaviour of the cells depends on the formation of the hyaluronate-binding Hermes-1 epitope rather than on the overall CD44s surface expression, which was virtually identical in all melanoma and melanocyte cell lines tested. Differences in the accessibility of the hyaluronate-binding epitope defined by Hermes-1 correlated with the phosphorylation state of CD44s, probably reflecting different activation states of the receptor. Furthermore, immunoprecipitation and pulse/chase studies revealed a three- to fivefold increase in CD44 synthesis in the highly aggressive melanoma cells as compared to the other cell lines and the melanocytes, indicating a reduction of CD44 half-life and up-regulation of turnover. Moreover, highly aggressive melanoma cell lines were found to shed significant amounts of CD44 from the cell surface and to secrete its ligand hyaluronic acid, which may refer to an "autocrine' mechanism mediating melanoma cell motility.

Animals↗
PubMed1996

Loss of adhesion to basement membrane components but not to keratinocytes in proliferating melanocytes.

We studied the adhesive characteristics of melanocytes, cultured either in the presence of the mitogen phorbol 12-myristate 13-acetate (PMA) that keeps them in a proliferative state, or in the absence of PMA allowing them to differentiate. On proliferating melanocytes, several integrins, ICAM-1, E-cadherin, and CD44 were expressed. In the absence of PMA, proliferation was arrested, melanin synthesis increased, and the morphology of the melanocytes became more spreaded. Under these conditions, expression of integrins alpha 3 beta 1 and alpha 5 beta 1 decreased, whereas expression of alpha 2 beta 1, alpha 4 beta 1, and alpha 6 beta 1 increased. No changes were observed for any of the other adhesion molecules. Immunoprecipitations from metabolically labeled cells confirmed the shift in integrin expression at the level of biosynthesis. The increased surface expression of alpha 2 beta 1 and alpha 6 beta 1 in the absence of PMA was accompanied by an induction of adhesion to basement membrane components collagen and laminin through these integrins. Integrin alpha 5 beta 1/alpha v beta 3-mediated adhesion to fibronectin, CD44-mediated adhesion to hyaluronate, and E-cadherin/beta 1-integrin-mediated adhesion to keratinocytes were not affected by PMA. These findings indicate that by selective modulation of the expression of adhesion molecules, adhesion to components of the basement membrane is reduced in proliferating melanocytes, whereas adhesion to keratinocytes is maintained. Similar events may be involved in melanocyte proliferation and migration during wound healing and initial steps of melanocytic tumor progression.

Basement Membrane↗