PDGFRB and pulmonary fibrosis: Early studies indicated that nintedanib inhibits the phosphorylation of vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), and fibroblast growth factor receptor (FGFR), as well as the TGF-β pathway, thereby delaying pulmonary fibrosis (Chaudhary et al., 2007; Hostettler et al., 2014; Wollin et al., 2014; Rangarajan et al., 2016).