P300/CBP mediates increased acetylation of H3K18 and H3K27 leading to hepatocellular carcinoma progression, and a novel P300 inhibitor, B029-2, exerts an antitumor effect by reducing amino acid metabolism and nucleotide synthase gene (including PSPH, PSAT1, ALDH18A1, TALDO1, ATIC, and DTYMK) promoter regions of H3K18Ac and H3K27Ac levels, leading to decreased chromatin accessibility and antitumor effects (15). The gene discussed is EP300; the disease is hepatocellular carcinoma.