. "C1510932"^^ . "Anti-ProgestinSYNCI" . "Progesterone AntagonistPTNCI" . "C1891"^^ . "antiprogestinPTNCI-GLOSSCDR0000561317" . "A substance that blocks the activity of a progestin.NCI" . "Chemical Viewed Functionally"^^ . . "Anti-progesteronesSYNCI" . "A substance that prevents cells from making or using progesterone (a hormone that plays a role in the menstrual cycle and pregnancy). Antiprogestins may stop some cancer cells from growing and they are being studied in the treatment of breast cancer. An antiprogestin is a type of hormone antagonist.NCI-GLOSS" . "Anti-Progestin"^^ . "Progesterone Antagonist"^^ . "Progesterone Antagonist"^^ .