In support of this, it could also be shown that TMZ chemoresistance in glioma cells was acquired by the nuclear accumulation of β-catenin and the upregulation of FoxO3a transcription factor [164], and by the activation of the Wnt/β-catenin signaling involving an ATM/CHK2-independent PI3K/AKT/GSK3β signaling cascade [165]. This evidence concerns the gene ATM and central nervous system cancer.