Accumulation of profibrotic myofibroblasts in fibroblastic foci (FF) is a crucial process for development of fibrosis during idiopathic pulmonary fibrosis (IPF) pathogenesis, and transforming growth factor (TGF)-β plays a key regulatory role in myofibroblast differentiation. The gene discussed is TGFB1; the disease is pulmonary fibrosis.