SMAD3 and idiopathic pulmonary fibrosis: Western blot analysis of lung-tissue lysates from independent donor, untreated biopsy, and IPF explant samples demonstrated higher phosphorylated SMAD3 (pSMAD3) expression in untreated ILD biopsies than in IPF explant samples (Supplemental Figure 2, B and C), consistent with the transcriptomic changes.