Troponin for the diagnosis of myocardial infarction, carcinoembryonic antigen (CAE) for various cancers, aminotransferases ALT and AST for liver diseases, and prostate-specific antigen (PSA) for the diagnosis and prognosis of prostate cancer are the best-known protein biomarkers detectable in blood [137]. The gene discussed is KLK3; the disease is myocardial infarction.