In prostate cancer, several markers such as prostate-specific antigen, prostatic acid phosphatase, prostate stem cell antigen and prostate-specific membrane antigen, which are all preferentially expressed by prostatic epithelial cells, have been demonstrated to serve as substrate sources of immunogenic peptide epitopes recognised by CTL (Correale et al, 1998; Peshwa et al, 1998; Dannull et al, 2000; Lu and Celis, 2002). The gene discussed is PSCA; the disease is prostate cancer.