Clayton Lau, M.D. (IMAGE) City of Hope Caption Clayton Lau, M.D., the Pauline & Martin Collins Family Chair in Urology and director of City of Hope's Prostate Cancer Program, is principal investigator of a Phase 2 clinical trial to investigate whether pills containing white button mushroom extract could regulate the immune system, affecting prostate-specific antigen (PSA) levels to either remain stable or decline. Heightened levels of PSA in men may indicate the existence of prostate tumors. Credit City of Hope Usage Restrictions Please use photo credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.