TGFB1 and polycystic ovary syndrome: To test this hypothesis, we first examined the activation of ER stress using granulosa cells from PCOS patients, the ovaries from PCOS patients, and the well-established dehydroepiandorosterone (DHEA)-treated PCOS mouse model, and then determined the in vitro effects of ER stress on TGF-β1 production in cultured human granulosa cells.