EP300 and hepatocellular carcinoma: Combined with the fact that the p300 and Ubc9 gene and protein expression levels were higher in HCC samples than in para-carcinoma samples (Supplementary Fig. 4i,j), it can be concluded that p300, through acetylating Ubc9 and facilitating acetylated Ubc9 binding to PEPCK1, could enhance PEPCK1 sumoylation, thus leading to lower PEPCK1 expression in HCC cells and clinical HCC samples.