Fourth, down-regulation of UBC9 resulted in a decrease in the expression of the anti-apoptotic proteins Bcl-2 and Bcl-xl as well as upregulation of the expression of the pro-apoptotic proteins cleaved-Caspase3 in HCC cells, which are important regulators of apoptosis and drug resistance [45]. Here, UBE2I is linked to hepatocellular carcinoma.