AKT1 and central nervous system cancer: Notch pathway also promotes the radioresistance of glioma stem cells as the Notch inhibition with gamma-secretase inhibitors (GSIs) induces the glioma stem cells to be more sensitive to radiation at clinically relevant doses due to the reduction of radiation-induced PI3K/Akt activation and upregulated levels of truncated apoptotic isoform of Mcl-1 (Mcl-1s) while not altering DNA damage response [93].