LGR5 and cancer: Additionally, CtBPs may directly coactivate TCF4/LEF at key target promoters (c-Myc, LGR5) to promote cancer stem cell self-renewal (18), indicating that CtBPs may activate Wnt signaling in cancer cells at multiple nodes-both by interacting with APC and several other genes that are associated with tumor initiation and growth, metastasis, and cancer stemness (15).