MAGE-C2/C3 (Melanoma-associated antigen C2, Hepatocellular carcinoma-associated antigen 587) is a 373 amino acid protein encoded by the human gene MAGEC2. Genes of the MAGE family direct the expression of tumor antigens that are recognized on human melanomas by autologous cytolytic T lymphocytes. Among tumor tissues, MAGE-C2/C3 is frequently expressed in seminomas, melanomas, and bladder transitional cell carcinomas. It is also expressed in a significant fraction of head and neck carcinomas, breast carcinomas, nonsmall-cell lung carcinomas, and sarcomas. In hepatocellular carcinoma, there is a inverse correlation between tumor differentiation and protein expression, i.e. the lower the differentiation, the higher percentage of expression. MAGE-C2/C3 is not expressed in normal tissues, except in germ cells in the seminiferous tubules and in Purkinje cells of the cerebellum. It is strongly expressed in spermatogonia and primary spermatocytes, however, at later stages of maturation, expression gradually decreases to become undetectable in mature spermatids.