KLK3 and malignant pleural mesothelioma: Clinically used soluble markers for cancer diagnosis include mesothelin in malignant pleural mesothelioma [3], colony stimulating factor-1 (CSF-1) [4] for endometrial carcinoma, prostate specific antigen (PSA) for prostate cancer [5], and carcinoembryonic antigen, CA125, for ovarian cancer [6].