The heatmap of these four biomarkers in the training set and test set were shown in Fig. 7A–B, which suggested that the expression level of FHL2 was correlated with IPF group positively, the expression level of SLAIN1, HPCAL1, and RNF182 were correlated with IPF group negatively. Here, SLAIN1 is linked to idiopathic interstitial pneumonia.