FOXO3 and central nervous system cancer: Similar to other forkhead box transcription factors, nuclear exportation of FOXO3 is dependent on its phosphorylation by protein kinase B (PKB, Akt) as a downstream member of PI3K/Akt signaling cascade [127, 180]; however, other protein kinases such as AMPK [181, 182], EGFR [183–185], and MAPK [186] can also regulate its activity in gliomas.