CASP9 and hepatocellular carcinoma: In terms of cell apoptosis, Liao et al. [34] reported that miR-155 is up-regulated in hepatocellular carcinoma, and the increased miR-155 can target FoxO3a expression and then inhibit bcl-2, caspase-3 and caspase-9 activities, thus inhibiting cell apoptosis and promoting cell proliferation in patients with hepatocellular carcinoma.