EGF and central nervous system cancer: The microglia, which are resident immune cells in the brain, will not kill tumor cells, they become tumor-associated microglia/macrophages (TAMs) in gliomas and typically exhibit an anti-inflammatory M2-type, and release cytokines, such as epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) to promote tumor growth [14].