VEGFA and pulmonary fibrosis: The occurrence and development of pulmonary fibrosis are regulated by many signal pathways, including the TGF-β/Smad signal pathway, Wnt/β-catenin signal pathway, PDGF signal pathway, phosphoinositide-3-kinase (PI3K)-protein kinase B (Akt) signal pathway, vascular endothelial growth factor (VEGF) signal pathway, and the fibroblast growth factor (FGF) signal pathway.