TGFB1 and pulmonary fibrosis: Abnormal tissue repair and fibrotic hyperplasia in IPF are affected by various cytokines in the microenvironment, among which the transforming growth factor-β1 (TGF-β1) signaling pathway is currently recognized as the most important fibrotic signal and plays a master-switch role in the pathogenesis of pulmonary fibrosis 8.