KLK3 and prostate cancer: In a phase I study on men with elevated PSA level in recurrent prostate cancer, pulverized muscadine grape skin extract (MPX) containing 4,000 mg resveratrol, compared with placebo, delayed the development of recurrence by lengthening the prostate specific antigen doubling time (PSADT) by 5.3 months (Paller et al., 2015).