RTN4 and pulmonary fibrosis: In order to determine whether protein expressions were associated with pulmonary fibrosis, Immunohistochemistry (IHC) was applied to examine the difference in the expression level of Nogo-b in lung samples of mice between the group treated with BLM and the untreated control, It was found that the lung mesenchyme in the mice treated with BLM showed a stronger brown staining for Nogo-b (Figure 1D) than that for the normal group (Figure 1C), indicating that high expression of Nogo-b is one of the features for the fibroblastic foci induced by BLM.