Most differentiation antigens have been identified in melanoma cells (e.g., Melan-A/MART-1, gp100/pmel17, tyrosinase, or TRP2 [20–22]) and prostate cancer cells (e.g., prostate-specific antigen and prostatic acidic phosphatase [23, 24]). The gene discussed is MLANA; the disease is prostate carcinoma.