To elucidate the mechanism of this anti-fibrotic action, we investigated the effect of natriuretic peptides on fibroblast differentiation (into highly synthetic and contractile αSMA-expressing myofibroblasts), which underpins the synthesis and deposition of extracellular matrix and is perceived to be a key step in the development of IPF (Burgess et al., 2005; Scotton and Chambers, 2007). Here, ACTA1 is linked to idiopathic pulmonary fibrosis.