As recent studies suggest that TMZ can significantly increase driver mutations in recurrent glioma, particularly in the retinoblastoma and Akt-mTOR pathways [38], we examined the activity of these pathways by measuring the phospho-protein levels of p90RSK, Akt, p44/42 MAPK (Erk1/2) and S6 ribosomal protein. Here, RPS6 is linked to central nervous system cancer.