MTOR and central nervous system cancer: As a critical central regulator of multiple oncogenic signals, aberrant activity of mTOR and downstream effectors including S6K and 4EBP1 is significantly higher in GBM in comparison to low grade glioma (Fig. 1C), implying that AKT and mTOR effector activity may be emerging as novel prognostic markers of glioma malignancy [107, 108].