VEGF–VEGFR1 is an extremely important signaling pathway in tumor neovascularization, and VEGF binding to VEGFR1 promotes vascular endothelial cell mitosis by activating phospholipase C and stimulating second messenger formation, inducing fibrinolytic zymogen degradation, participating in basement membrane degradation and extracellular protein hydrolysis, and increasing vascular permeability. This evidence concerns the gene FLT1 and neoplasm.