UBA3 and hepatocellular carcinoma: As shown in Figure 1A, a significant increase in the mRNA expression of NEDD8, NEDD8-activating enzyme E1 (NAE1 and UBA3), NEDD8-conjuagating enzyme E2 (UBE2M), or NEDD8-E3 ligase (RBX1) was detected in HCC tissues compared with normal liver tissues.