HSPB1 and idiopathic pulmonary fibrosis: Although there are several controversies about the similarity and differences of pathological mechanisms between IPF and RIPF [34, 35], HSP27 expression is well recognized to be increased in lung tissues of IPF [11, 12] and animal models of BLM-induced lung fibrosis [9], as well as an RIPF animal model and RIPF patients in this study.