Broadly acting HAT inhibitors such as PU139 and PU141 decreased proliferation and activated apoptosis in vitro in various cancer types including ovarian carcinoma, hepatocellular carcinoma, and colon adenocarcinoma through blocking GCN5, p300/CBP, and cAMP-Responsive Element-Binding Protein 1 (CREB) activity. The gene discussed is EP300; the disease is cancer.