TGFB1 and pulmonary fibrosis: On the other hand, we have metformin, an anti-diabetic drug not known primarily for its antioxidant potential, but a recent study has demonstrated that treatment with metformin inhibits TGF-β1–induced Nox4 expression, ROS generation and myofibroblast differentiation in lung fibroblasts in vitro and also attenuates bleomycin-induced lung fibrosis (Sato et al., 2016; Rangarajan et al., 2018).