KG-501 is a CREB inhibitor, with an IC₅₀ of 6.89 μM. IC50 & Target: IC50: 6.89 μM (CREB)^[1]. In Vitro: KG-501, which directly targets the KIX domain of CBP, results in a disrupted CREB-CBP complex, inhibits CREB-target gene induction, and inhibits IL-1β-mediated angiogenic activity in NSCLC^[1]. KG-501 disrupts phospho (Ser-133) CREB binding to KIX with a K_i of ~90 μM, using concentrations of CREB that are within the linear range of the binding assay. Treatment of HEK293T cells with KG-501 also blocks induction of endogenous CREB target genes (NR4A2, αCG, c-fos, and RGS2) by forskolin, indicating that KG-501 likely exerts a general effect on CREB activity^[2]. KG-501 can also inhibit NF-κB transcription activity because NF-κB also uses CBP as a cofactor to regulate gene expression. The migration of HUVECs induced by CM from A549 cells treated with IL-1β plus 10 μM of KG-501 is significantly lower than that induced by CM from A549 cells treated with IL-1β alone. At 10 μM, KG-501 suppresses the expression of all of the IL-1β–induced CXC chemokine genes except CXCL8. For the protein level, KG-501 significantly suppresses IL-1β–induced CXCL5 protein secretion. Similar effects of KG-501 are also observed in the H1734 cell line^[3].