Although Yokota (one of the authors of the present manuscript) et al. previously reported that the serum levels of HSP47 did not differ significantly between patients with IPF and healthy controls[28], we recently reported that HSP47 serum levels in patients with acute exacerbation of IPF were found to be markedly higher than in patients with stable IPF[23]. The gene discussed is SERPINH1; the disease is idiopathic pulmonary fibrosis.