MFN1 and pulmonary fibrosis: These findings confirm that defective lipid metabolism in AEC2 cells promotes bleomycin-induced lung fibrosis, and supports our hypothesis that impaired regulation of lipid metabolism in AEC2 cells of Mfn1iΔAEC2, Mfn2iΔAEC2, and Mfn1/2iΔAEC2 mice contributes to development of lung fibrosis (Supplementary Fig. 16).