CREBBP and osteosarcoma: To prove that Wnt activation is necessary for osteosarcoma growth, colony formation, invasion, and metastasis, we first treated human OS cells with PRI-724 (an ICG-001 derivative), a small molecule inhibitor of CBP (CREB binding protein)/β-catenin complex formation, which suppresses Wnt/β-catenin-mediated transcription [25].