LGR5 and colon adenoma: In colon cells, LGR5, a WNT signalling component, initiates an intestinal stem cell (ISC) program; however, abnormal LGR5 expression does not initiate premalignant colon adenomas unless other genes, e.g., APC or CTNNB1 (β-catenin), are also mutated to drive aberrant WNT signalling.