TGFB1 and pulmonary fibrosis: Transforming growth factor-β1 (TGF-β1), as a pleiotropic cytokine generated by activated immune cells and alveolar type I or II epithelial cells, has been reported to be crucial in the pulmonary fibrosis as it can promote the activation of myofibroblasts, proliferation of fibroblasts, and deposition of extracellular matrix (ECM) [7–9].