SMAD2 and polycystic ovary syndrome: One study has proven that a potent ALK5 inhibitor, namely SB431542, can inhibit related molecules, such as TGF-β, Smad3, Smad2, and a-SMA, and upregulates anti-fibrotic factor MMP2 in rats with DHEA-induced PCOS, thereby mitigating ovarian fibrosis via the TGF-β/Smads signaling pathway (283).