Beta-catenin is a pivotal player in the signaling pathway initiated by Wnt proteins, mediators of several developmental processes. beta-catenin activity is controlled by a large number of binding partners that affect the stability and the localization of beta-catenin and is thereby able to participate in such varying processes as gene expression and cell adhesion. Activating mutations in beta-catenin and in components regulating its stability can contribute to the formation of certain tumors.