beta-Catenin is one of the E-cadherin associated proteins involved in the process of cellular adhesion. It has recently been shown to interact with the APC protein whose gene is known to be mutated in the germline of familial adenomatous polyposis patients. This interaction implies that beta-catenin is a potential regulator of the APC gene. The localization of the human beta-catenin gene (CTNNB1) to chromosome 3p22, by fluorescent in situ hybridization (FISH), has linked the gene to a region that is frequently altered in several human malignancies. The location of the gene and the protein interactions suggest the importance of beta-catenin in the etiology of various human cancers.