TGFB1 and pulmonary fibrosis: As for fibrotic diseases, circPVT1 knockdown repressed the levels of transforming growth factor-beta 1 (TGF-β1), α-smooth muscle actin (α-SMA), and connective tissue growth factor induced by hypoxia, thus ameliorating the development and progression of bladder fibrosis[15], but the role of circPVT1 in the silica-induced pulmonary fibrosis remains to be investigated.