COPS5 and hepatocellular carcinoma: Suberoylanilide hydroxamic acid, an HDAC inhibitor, effectively reduces the pro-oncogenic effect of the hepatitis B virus pre-S2 mutant oncoprotein in hepatocellular carcinoma cells and promotes the generation of the tumor suppressor protein thioredoxin-binding protein 2 (TBP2), which consequently strengthens the association between JAB1 and TBP2, and suppresses the degradation of p27 triggered by pre-S2 mutants [31, 32].