The 20–22 kDa protein doublet that this antibodyrecognises is known as Melan-A or MART-1 (MelanomaAntigen Recognised by T cells 1). Autologous cytotoxic Tcells recognise MART-1, a recently discovered melanocytedifferentiation antigen. Autologous cytotoxic T cells canalso recognise seven other melanoma-associated antigens:tyrosinase, MAGE-1, MAGE-3, gp100, gp75, BAGE-1, andGAGE-1. MART-1 is found in the endoplasmic reticulum andmelanosomes, according to subcellular fractionation.Melanomas and other tumours exhibiting melanocyticdifferentiation are labelled by this MAb. Additionally, it is ahelpful positive indicator for angiomyolipomas. Tumourcells of mesenchymal, glial, lymphoid, or epithelial originare not stained by it.