Thus, proteins(or genes) that are expressed differently in cancer cells than inhealthy cells or in a mutated form are targets for immunotherapies.The following discussion covers a number of tumor-associated antigens,including mucin 1 (MUC1), human epidermal growth factor receptor 2(HER-2), cancer–testis antigen 1 (NY-ESO-1), melanoma antigenrecognized by T cells 1 (Melan-A or MART-1), prostate-specific antigen(PSA), and others. The gene discussed is KLK3; the disease is cancer.