In contrast, as a target gene relevant to execution and completion of apoptosis, the overexpressed CDKN1A triggered by HBx-induced HDAC4 inhibition was concordant with the earlier research that HBx can relieve a block on CDKN1A expression and prolong G1→S transition in human hepatoma cells [156,157]. The gene discussed is CDKN1A; the disease is hepatocellular carcinoma.