A protein found on normal melanocytes (cells that make the pigment melanin) in the skin and in the retina. It is also found on most melanomas (cancers that begin in melanocytes). Vaccines using pieces of the Melanoma Antigen Recognized by T cells 1 are being studied for their ability to boost the immune response to cancer cells in patients with melanoma. Also called MART-1 antigen and Melan-A protein.