TGFB1 and pulmonary fibrosis: Connective tissue growth factor (CTGF) and plasminogen activation inhibitor 1 (PAI-1) were also induced by TGF-β1 (CTGF: 21.73 ± 1.54; PAI-1: 54.40 ± 5.48; p < 0.05) and are thought to play important roles in pulmonary fibrosis [6,18].