Nintedanib has been suggested to be effective in IPF because it inhibits platelet-derived growth factor receptor (PDGFR), vascular endothelial growth factor receptor (VEGFR), and fibroblast growth factor receptor (FGFR), but it also inhibits some nonreceptor tyrosine kinases, such as Src, Yes, and Lck (41). This evidence concerns the gene SRC and idiopathic pulmonary fibrosis.