Indeed, blockade of Smad signalling appears a common theme in the anti-TGFβ effects of natriuretic peptides since this phenomenon is observed in cardiac fibroblasts, proximal tubular cells and pulmonary artery smooth muscle cells (Kapoun et al., 2004; Li et al., 2008; Lo et al., 2008); whether a similar intervention underlies the beneficial effects of combination therapy in pulmonary fibrosis warrants further attention. This evidence concerns the gene TGFB1 and pulmonary fibrosis.