UGT1A9 and prostate cancer: While estrogen glucuronidation has not been extensively studied as a pathway in either breast or prostate cancer, activities of glucuronidation enzymes on estrogenic compounds have been reported and differ between estradiol and estrone (E2; UGT1A1, UGT1A4, UGT1A9, and UGT1A10 E1; UGT1A9, UGT1A10, UGT1A3, and UGT1A8) (11, 24).