While there may be multiple pathways to tumor initiation, it has been shown that the inactivation of a single tumor suppressor gene (TSG) such as the adenomatous polyposis coli (APC) gene in colon is sufficient to abrogate crypt homeostasis, leading to the formation of aberrant crypts and nascent adenomas (Humphries & Wright, 2008). The gene discussed is APC; the disease is adenoma.