High affinity and selective cell-permeable p300/CBP-associated factor (PCAF) inhibitor (Ki = 47 nM). Exhibits no significant activity against a panel of 48 other bromodomains except GCN5 (Kd = 600 nM). Exhibits >4500-fold selectivity for PCAF over BRD4. Also exhibits metabolic stability in mouse and human liver microsomes and no observable cytotoxicity in peripheral blood mononuclear cells (PBMC). Purity 98%. MW (observed): 433.38