FOXO3 and cancer: Inhibition of PI3K/AKT signaling pathway by down-regulating the level of p-AKT significantly activates FOXO3a which suppresses the expression of CCND1 and other related cell cycle regulators by inducing the up-regulation of tumor suppressing genes (p21 and p27) and finally inhibits the proliferation of cancer cells [33–35, 42].