In the tumor microenvironment, the GSCs can secret cytokines such as fibroblast growth factor 2 (FGF2), hypoxia-inducing factor (HIF), and vascular endothelial growth factor (VEGF) to promote tumor invasion, recruit immune cells, induce angiogenesis, and self-renew (Hambardzumyan and Bergers, 2015). Here, VEGFA is linked to neoplasm.