PLXNA4 and idiopathic interstitial pneumonia: For mRNAs, the expression levels of DDX11, E2F1, NPTX1, and PLXNA4 were significantly lower in nintedanib-treated IPF fibroblasts than in controls, and the expression levels of SLC25A23 were significantly higher in nintedanib-treated IPF fibroblasts than in controls (Figure 7A).