In idiopathic pulmonary fibrosis, NOX4 also mediates TGF-β-induced fibroblast differentiation into myofibroblasts [8] and contributes to myofibroblast differentiation by activating multiple signal pathways such as Smad 2/3 phosphorylation, JNK, and P38MAP kinase [7]. Here, NOX4 is linked to idiopathic pulmonary fibrosis.