TGFB1 and polycystic ovary syndrome: Taken together with the findings that ER stress causes the activation of TGF-β signaling and fibrosis in various organs (74–76), it is conceivable that ER stress activated by HA in the ovaries of women with PCOS is implicated in the etiology of the interstitial fibrosis that characterizes the ovaries of women with PCOS.