In IPF patients, Nox4 is strongly expressed in fibroblast foci and increases the expression of α-smooth muscle actin (α-SMA), fibronectin and procollagen, which are the most characteristic profibrotic molecules (Griffith et al., 2009; Hecker et al., 2009; Amara et al., 2010). Here, ACTA1 is linked to idiopathic pulmonary fibrosis.