Potent and selective BRD4 bromodomain inhibitor (Ki = 30 - 50 nM for the first bromodomain (BRD4(1)). Exhibits 10-fold selectivity for BRD4(1) over BRD4(2). Blocks BRD4 transcriptional activity in lipopolysaccharide-induced production of both nitric oxide and IL-6 in mouse macrophages (IC50 values are 3.8 and 4.9 μM, respectively). Attenuates melanoma cell proliferation in vitro. Purity 98%. MW (observed): 383.42