Several in vivo studies have demonstrated that the presence of CSCs (CD133 positive) in GBM correlated with chemoradioresistance and a poor prognosis [48], whereas Melguizo et al. [11] recently demonstrated that CD133 has no implication in the prognosis of GBM patients, supporting similar findings reported by Kim et al. [49]. This evidence concerns the gene PROM1 and glioblastoma.