FOXO3 and hepatocellular carcinoma: Interestingly, we observed that FOXO3a was downregulated in serum-deprived HCC cells, and that knockdown of FOXO3a enhanced the sensitivity of HCC cells to serum deprivation and overexpression of active FOXO3a reversed the serum-deprivation-induced proliferative inhibition, indicating that FOXO3a is required for serum-deprived HCC cells to maintain normal growth.