Damaged AECs produces many kinds of profibrotic mediators, such as transforming growth factor beta 1 (TGF-β1), connective tissue growth factor (CTGF), platelet-derived growth factor (PDFG), etc., that promote a profibrotic microenvironment in the lungs of IPF patients. The gene discussed is CCN2; the disease is idiopathic pulmonary fibrosis.