TGFB1 and idiopathic pulmonary fibrosis: Additionally, an increasing number of studies have confirmed that TGF-β1 is a fundamental pathological mechanism, which contributes to the progression of IPF by promoting the transformation of fibroblast into myofibroblast, epithelial cells into mesenchymal cells, the production of collagen, filamentous actin, and α-SMA (37).