Fig. 1

OPN is highly expressed in the lung tissue of IPF patients and is associated with the prognosis of patients. A Volcano plot visualizing the DEGs in GSE70866. The x axis indicates the fold change (log-scaled), whereas the y axis shows. Vertical lines represent either upregulation or downregulation by twofold. The horizontal line represents a p-value = 0.05. Red points represent upregulated (up) genes, gray points stand for no-significantly-changed (NSC) genes, and blue points represent downregulated genes. B Box plot shows the difference of the level of OPN expression between control group and IPF groups in GSE70866, p < 0.0001. C The lung biopsy tissue sections of IPF and donor were subjected to immunohistochemical staining of OPN. Bar, 100 μm. D The survival time of IPF patients was linearly correlated with the expression level of OPN in GSE70867, p < 0.0001. E ROC curves for forecasting overall survival, p < 0.0001. F Kaplan–Meier plot of overall survival between OPN high and OPN low groups in GSE70867