In mammalian cells,FoxO factors act as potent transcriptional activators that upregulate the expression of programs of genes involved in stress resistance,cell cycle arrest,differentiation,apoptosis,autophagy,and metabolism. FOXO3 has a key role in the maintenance of adult neural and hematopoietic stem cells. It also associates with extreme longevity in humans and regulates the homeostasis of adult stem cell pools in mammals,which may contribute to longevity. Phosphorylation inhibits FOXO3 nuclear translocation that is essential for its regulation and function