ACP3 and prostate cancer: PAP, Galectin-3, and Secernin-1. Three proteins in our initial 2D-DIGE and MS experiments were found to be associated with prostate cancer (secernin-1, PAP, and galectin-3) were chosen for a proof of principal MRM-MS study, using urine from nine prostate cancer patients without relapse and seven patients with relapse.