SMAD3 and pulmonary fibrosis: Smad3 and p-Smad3 are involved in TGF-β1-induced fibrotic gene responses as well as in BLM-induced pulmonary fibrosis, p-Smad3 is responsible for TGF-β1 fibrosis activation and alpha-smooth muscle actin (α-SMA) is one of the key indicators of fibrotic lung diseases [30]–[33].