P501s (Prostein) in Prostate Cancer
P501s is a protein localized to the Golgi complex in both benign and neoplastic prostate. The staining pattern is speckled and perinuclear (the location of Golgi). Its expression is retained in high-grade as well as metastatic prostate cancer. It is a useful addition to a panel containing PSA and prostatic acid phosphatase for differentiating high-grade prostate cancer from other high-grade urothelial or colo-rectal carcinomas.