In Vitro: MART-1 (Melan-A) gene is 18 kb long and comprises five exons. It is expressed in most melanoma tumor samples, and among normal cells, only in melanocytes . In cancer immunotherapy, epitopes and variants derived from the MART-1/Melan-A protein are widely used as clinical vaccines. The epitopes spanning amino acid residues 26–35 and 27–35 from the MART-1/Melan-A protein, highly expressed in melanoma cells, provide a prime example of T cell recognition of multiple peptides and the use of peptide variants designed to elicit altered immunological responses.