EGF and glioblastoma: Several groups announced that GBM spheres created in serum-free medium with EGF and bFGF had the ability to be highly invasive, to proliferate and retain their multipotency; that is, they can differentiate into cells expressing astrocytic, oligodendroglial and neuronal markers, through binding to the EGF and FGF receptors and triggering the corresponding signal transduction pathways [6,7,10].