Identification of a melanoma progression antigen as integrin VLA-2. The expression of the integrin receptors VLA-1, -2, -3, and -6 was studied in normal cultured melanocytes and in five melanoma cell lines. Normal melanocytes synthesized VLA-3, but did not reveal detectable levels of VLA-1, -2, and -6. All melanoma cell lines, however, expressed VLA-2, -3, and -6. VLA-1 was synthesized by two of five melanoma lines. In parallel, we had analyzed the expression of four previously characterized melanoma cell surface antigens. One of them (antigen A.1.43), which is associated with tumor progression of human melanoma, revealed a striking similarity to VLA-2. In sequential immunoprecipitation experiments, we show that A.1.43 is identical with the integrin VLA-2, a cell surface receptor for collagen, laminin, and fibronectin. 