FOXO3 and cancer: The mammalian forkhead subclass O (FoxO) family members of transcriptional factors, such as FoxO1 (FHKR) and FoxO3a (FKHR-L1) are characterized by a distinctive forkhead DNA binding domain which function downstream of PI3K antagonist PTEN in cancer cells, inhibit cell cycle progression and promote cell death by modulating the expression of genes encoding apoptosis (9), growth regulatory proteins (10) and stress response (11,12).