KLK3 and neoplasm: Clinically high‐specific tumor markers include the alpha‐fetoprotein (AFP), the prostate specific antigen (PSA), the carcino‐embryonic antigen, the cancer antigen 15–3, and the cancer antigen 12–5, etc. Among them, AFP (molecular weight 70 kDa) is a typical serological biomarker glycoprotein with high specificity and sensitivity for the diagnosis and the treatment monitoring of the primary hepatocellular carcinoma (HCC).