TGFB1 and idiopathic pulmonary fibrosis: The correlations confirm that the increased TGF-β1 and β-catenin expression impact lung gas exchange capacity (DLCO) in IPF patients, which could indicate underlying PH complications in IPF patients, as reduced DLCO in IPF patients has been believed to be a concomitant PH indication as to the underlying pulmonary fibrosis [68,69].