CD9 and prostate cancer: Recentresearch has identified certain EV-related proteins as possible diagnosticand prognostic markers for prostate cancer, namely, prostate-specificmembrane antigen (PSMA), EpCAM, CD9, and STEAP1., In one study, researchers found elevated levels of PSMA in EVs derivedfrom prostate cancer cells compared to those derived from benign prostatictissue.