EGF and glioma: Activated microglia switch from a resting state toward an amoeboid phenotype and subsequently release several factors that promote glioma proliferation and migration, including stress-inducible protein 1 (STI1), epidermal growth factor (EGF), TGF-β, as well as IL-1β, which modulate the BBB to further allow invasion of peripheral immune cells into the CNS (85, 86).