LGR5 and colorectal carcinoma: Nevertheless, the frequent and CRC-specific mutations in the tumour suppressor adenomatous polyposis coli (APC) and its known function as an inhibitor of the Wnt signalling pathway that regulates Lgr5 expression provides one of the clearest examples of the close links between cancer driver mutations and homoeostatic stem-cell programmes as a critical determinant of tumour phenotypes, including metastasis-initiating potential.