In the pathogenesis of pulmonary fibrosis, Forkhead box protein O3 (FOXO3) inhibits fibroblast activation and ECM deposition via its interaction with TGF-β1-induced Smad3, thereby attenuating idiopathic pulmonary fibrosis (IPF) (93, 99). Here, FOXO3 is linked to idiopathic pulmonary fibrosis.