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). Here, KRAS is linked to glioblastoma.