MELAN-A/MART-1 is a melanocyte differentiation marker. 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. Seven other melanoma-associated antigens recognized by autologous cytotoxic T cells include MAGE-1, MAGE-1, tyrosinase, gp100, gp75, BAGE-1, and GAGE-1.