KLK3 and prostate cancer: The Select MDx assay (MDx Health) combines expression levels from HOXC6 (a prostate cancer progression gene), DLX1 (a prostate cancer cell proliferation gene), KLK3 (a prostate cancer reference gene) along with clinical parameters such as age, digital rectal examination [DRE] findings, PSA levels and prostate volume, in a logistic regression model.12