AKT1 and central nervous system cancer: Mutations in the PTEN gene have also been demonstrated to commonly occur in gliomas (Cantley and Neel, 1999; Sano et al., 1999; Zundel et al., 2000; Fan et al., 2002), leading to loss of negative regulation on the phosphatidylinositol-3 kinase (PI3K)/Akt pathway.