CDKN1A and Familial prostate cancer: Previous studies have found that AR has a role in apoptosis regulation in prostate cancer,18, 19 and both p21Cip1 and AKT are involved in AR-regulated apoptosis.20, 21, 22, 23 Using western blotting analysis, we found that treatments with the phthalate esters DEHP, DBP, and BBP reduced the AR expression level to 40, 55, and 45%, respectively, relative to the level of the DMSO-treated control (Figure 4b).