NEDD8 and hepatocellular carcinoma: The results of qRT-PCR and western blotting showed that, compared to the control group, the mRNA level of NEDD8 was unchanged, but its protein level was increased in the HCC cells of the shNUB1 group and decreased in the HCC cells of the Flag-NUB1 group (Fig. 4D and Supplementary Fig. 2F).