In addition to the data from autopsy sections, Iwashita et al. reported a higher expression of HSP47 and type I procollagen in patients with IPF by using immunohistochemistry on sequential sections compared to expression in cryptogenic organizing pneumonia (COP), which is considered a weak type of fibrosis compared with IPF among idiopathic interstitial pneumonias (IIPs). This evidence concerns the gene COL1A2 and idiopathic pulmonary fibrosis.