Since both types of PRG receptors and their modulators can be predominant targets for breast cancer therapy (58), as an antiprogestin (36, 59–63) [one of the well-known common contraceptives (60–65)], mifepristone (MIF, RU486, antiprogestin) has certainly earned its candidacy in the treatment of reproductive cancers (58, 66–68) such as breast, prostate, ovarian, and endometrial cancers, and has been previously studied in many clinical trials (59, 62, 63, 69). This evidence concerns the gene MIF and breast cancer.