A differential display method was used to study genes the expression of which is altered during growth inhibition induced by medroxyprogesterone acetate (MPA). A tran-script of G-protein-coupled receptor 30 (GPR30) was upregulated by MPA in estrogen-treated MCF-7 breast cancer cells. Northern-blot analysis showed a progestin-specific primary target gene, which was enhanced by prog-esterone and different progestins, but not by dihydrotestos-terone or dexamethasone, and which was abrogated by antiprogestin RU486
