TP53 and glioblastoma: For instance, following the exposure of p53−/− mice to the mutagen n-ethyl-n-nitrosourea (ENU), glioblastoma-like tumors can form in periventricular locations and are characterized by enhanced NSCs self-renewal, recruitment to the fast-proliferating progenitor population (type C) and impaired differentiation (Gil-Perotin et al., 2006).