Mifepristone is a progesterone and glucocorticoid receptor antagonist (Ki = 0.64 and 0.1 nM, respectively; Attardi et al.; Song et al.; von Geldern et al.). It has been reported that Mifepristone is used in the treatment of leiomyomata, endometriosis, breast cancer, and meningioma (Mahajan et al.).CANCER RESEARCH· Inhibits the expressions of cyclin-dependent kinase 1 (CDK1) and cyclin-dependent kinase 2 (CDK2), leading to cell cycle arrest and apoptosis in endometrial epithelial cells and stromal cells in adenomyosis (Che et al.).· Induces cell cycle arrest and apoptosis in antiestrogen-resistant breast cancer cells in vitro (Gaddy et al.).