PMEL and cancer: TAAs include: cancer/germline antigens (also known as cancer/testis or CT antigens), which are normally expressed only in immune privileged germline cells (e.g., MAGE-A1, MAGE-A3, and NY-ESO-1);10–14 cell lineage differentiation antigens, which are normally not expressed in adult tissue (e.g., tyrosinase, gp100, MART-1, prostate-specific antigen (PSA), and prostatic acid phosphatase (PAP));15–19 and antigens that are overexpressed in cancer cells (e.g., hTERT, HER2, mesothelin, and MUC-1).20–23 Several hurdles are associated with developing vaccines against TAAs.