The clinical potential of MC2-specific T cells is exemplified by a high frequency of MC2/A2-specific CTL (10−4 of CD8 T cells) observed in the blood of a melanoma patient whose tumors regressed after vaccination with MAGE-A1 and A3 peptides, whereas in the same patient the frequency of anti-vaccine CTLs was low (3 × 10−6 of CD8 T cells) [37]. The gene discussed is MC5R; the disease is melanoma.