GFAP and glioblastoma: We exposed to 10 Gy irr a murine glioblastoma (GBM) cancer stem cell line (GL261-CSC), which carries point mutations in K-Ras and p53 (Szatmári et al., 2006), expresses Nestin but not GFAP, and can be grown as adherent cultures as well as tumorspheres (Pellegatta et al., 2006).