In prostate cancer (PCa), several proteins have been identified as preferentially expressed by malignant cells, including prostate-specific antigen (PSA), prostatic acid phosphatase (PAP), prostate stem cell antigen (PSCA), T-cell receptor gamma alternate reading frame protein (TARP), transient receptor potential (trp)-p8, and prostate-specific membrane antigen (PSMA). This evidence concerns the gene KLK3 and prostate cancer.