TGFB1 and pulmonary fibrosis: The FIEL1 inhibitor BC-1485, which also binds to the substrate PIAS4 in the HECT domain region, shows potent antifibrotic properties by stabilizing PIAS4 and suppressing TGF-β signaling in both murine models of pulmonary fibrosis and human MRC5 cells (95, 96).