Regardless of whether treatment initiates quiescence in GBM, in our dataset the longest survivals were observed in patients with high SOX2 or CD133 levels and methylated MGMT. This suggests that a critical effect of TMZ therapy in GBM may be dependent on the presence of stem cells, and has less effect in tumors with a low component of this cellular phenotype. This evidence concerns the gene PROM1 and glioblastoma.