BRD4 and pulmonary fibrosis: The interaction of BRD4 and TGF-β signaling has been reported in different cell types, including epithelial cells, fibroblasts, cardiomyocytes, etc. In addition, BRD4 also mediates TGF-β-induced fibroblast activation in the context of cardiac fibrosis [16,17] and pulmonary fibrosis [18].