Fig. 2

Association between HE4 expression and clinical characteristics of IPF patients. Data are shown for correlation between HE4 gene expression and A age, B gender, and C GAP index in training set; and D–F in validation set. The protein levels of HE4 in different subgroups of G age, H gender, and I GAP index. *p < 0.05, **p < 0.01, ns: non-significant