EGF and neoplasm: In turn, Microglia/TAM secrete a number of growth factors, including platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-β), epidermal growth factor (EGF), and fibroblast growth factor 2 (FGF-2), that can activate STAT3 signaling in tumor cells and GSCs, enhancing their growth and progression [51].