UBE2I and hepatocellular carcinoma: Consistent with the vital role of SUMO proteins and the UBC9 in SUMOylation [17,18,19,20,21], we further demonstrated that similar to SAE1, the expression levels of SUMO1, SUMO2, and UBC9 were upregulated in the HCC tissues compared to their non-tumor paracancerous counterparts (Figure 3C).