MART-1 (also known as Melan-A) is a melanocyte differentiation antigen or marker recognized by autologous cytotoxic T lymphocytes. It is a membrane protein with one transmembrane peptide. Melan-A is expressed by a large proportion of melanoma tumors, both melanotic and amelanotic and by melanoma cell lines. It is present in melanocytes of normal skin and retina, nevi and in more than 85% of melanomas. Melan-A/MART-1 is not expressed by non-melanoma malignancies. It is recognized by autologous cytotoxic T lymphocytes. Subcellular fractionation shows that MART-1 is present in melanosomes and endoplasmic reticulum. Six other melanoma associated antigens recognized by autologous cytotoxic T cells include MAGE-1, Tyrosinase, gp100, gp75, BAGE-1,