NiCur is an effective and selective inhibitor of CBP histone acetyltransferase (HAT), with an IC50 of 0.35 µM. NiCur blocks CBP HAT activity, downregulates p53 activation and inhibits apoptosis, while promoting methylation of Lysine 27 on histone H3, inhibiting Caspase 3 activity and PARP cleavage.