CYP24A1 and endometrial cancer: Because progesterone and progesterone derivatives are used to treat endometrial cancer, we examined the effects of progesterone (PROG), medroxyprogesterone acetate (MPA), norestrel (NORG), norethindrone (NOR), and calcitriol, either alone or in combination, on CYP24A1 transcript expression in HEC-1B, Ishikawa, and RL-95 cells.