In this study, we demonstrated that pirfenidone treatment at concentrations of 50μM (~9.2 μg/ml) reduced the TGF-β1-induced SMAD3 nuclear accumulation in ATII cells from healthy donors and primary lung fibroblasts from IPF patients, as well as, the SBE DNA activation in A549 cells. Here, TGFB1 is linked to idiopathic pulmonary fibrosis.