PTGS2 and polycystic ovary syndrome: iNOS, cyclooxygenase-2 (COX-2), and transforming growth factor (TGF)-β activity were increased in the ovaries of PCOS patients (Elia et al., 2006; Hatzirodos et al., 2011), and iNOS and COX-2 activity were prevented by metformin administration (Elia et al., 2006).