SMAD1 and polycystic ovary syndrome: It has been reported that in PCOS cumulus cells, 65% of genes related to the TGF beta signalling pathways were down-regulated, including several members of the TGF beta superfamily, type II TGF beta receptors and their targets SMAD1/5, as well as the TGF beta receptor III (TGFBR3) [18].