The adenomatous polyposis syndromes, familial adenomatous polyposis (FAP) and Gardner’s syndrome (GS), are characterized by numerous adenomatous polyps throughout the entire colon. These polyps invariably progress to colon cancer in addition to other extracolonic manifestations. The cloning of the APC gene revealed a ubiquitously expressed protein, 2843 amino acids in length, which is frequently mutated in patients suffering from FAP and GS. APC has been found to be associated with structural components of intracellular junctions. b-catenin and g-catenin (also called plakoglobin) are involved in the regulation of cellular adhesion. APC and E cadherin compete for binding to specific internal regions of both b- and g-catenin. Interactions between cytoskeleton and the APC, E cadherin, b/g catenin complex are mediated by a-catenin.