TGFB1 and pulmonary fibrosis: Typically, mammals express three homologous TGF-β subtypes (TGF-β1, TGF-β2, TGF-β3), among which TGF-β1 is most relevant to fibrosis.In fibrotic diseases, TGF-β1 is frequently upregulated and activated: it stimulates fibroblast proliferation and collagen production around silica particles—thereby promoting the development of pulmonary fibrosis and silicotic nodules—and triggers fibroblast-to-myofibroblast transition (FMT) to drive extracellular matrix (ECM) deposition (Wang et al., 2020).