ICG 1 is a small molecule inhibitor that targets Wnt/β-catenin pathway. It inhibits TCF/β-catenin mediated transcription by competing with β-catenin for CBP (CREB binding protein) but not p300 binding with an IC50 of 3 µM. It can be used to specifically evaluate the role of CBP/beta-catenin association on WNT signaling and cell physiology.