Notably, it has been reported that PI16 was one of the most abundant proteins secreted by the epithelial cells of the prostate lumen and was also present in other body fluids, and the serum level of PI16 can predict the risk level of prostate cancer [23, 24], further elucidating the fundamental potential of PI16 as a minimally invasive diagnostic marker. The gene discussed is PI16; the disease is prostate cancer.