Purity >98%. The bromodomain and PHD finger-containing (BRPF) proteins are scaffolding components of chromatin-binding MOZ/MORF histone acetyltransferase complexes, which have activity as transcriptional regulators. BRPF1 (BR140 or Peregrin) is important for maintaining Hox gene expression and the development of multiple tissues, axial skeleton, and the hematopoietic system. GSK5959 is a potent, cell-permeable inhibitor of the BRPF1 bromodomain (IC50 = 80 nM). It exhibits greater than 100-fold selectivity for the BRPF1 bromodomain over a panel of 35 other bromodomains. GSK5959 disrupts chromatin binding of BRPF1 in a cellular assay by blocking the interaction of BRPF1 with histone H3.3.