TGFB1 and pulmonary fibrosis: TGF-β1 activates HMGB1, RELM-β, Slit2, and Fstl1 by cooperating with Smad2 and Smad3 and influences the three steps of idiopathic pulmonary fibrosis (EMT, myofibroblast differentiation, and fibrogenesis) [38] (Figure 2).