HGF and central nervous system cancer: Microglial cells recruited by glioma can promote tumor growth [25], [26], [27], dictated by paracrine loops responsible for glioma initiation and progression (e.g., IL-6, IL-10, TGF-β, prostaglandins, G-CSF, and GM-CSF, and growth factors such as EGF, VEGF, HGF, and SCF).