Mifepristone. A progesterone receptor antagonist, Synonyms: 11beta-(4-Dimethyl-amino)-phenyl-17beta-hydroxy-17-(1-propynyl)-estra-4,9-dien-3-one, RU-486, RU-38486, CAS Number: 84371-65-3, Purity: G99% by Thin Layer Chromatography, Molecular Formula: C29HGGNO2, 50mg.