STEAP 1 is overexpressed in different stages of PCa as well as other tumors including bladder, colon, and ovarian cancer.45,49 Human kallikrein 2 (hK2) is a serine protease encoded by the KLK2 gene that is expressed in both malignant and nonmalignant prostate tissue. The gene discussed is KLK2; the disease is ovarian cancer.