Once upon a time there was (beta)-catenin in cadherin-mediated signalling

(beta)-Catenin was initially characterized as a protein interacting with the cadherin cytoplasmic tail and regulating cell-cell contacts and actin cytoskeleton interactions. Moreover, the gene coding for the Drosophila orthologue of (beta)-catenin, armadillo, was independently identified downstream of wingless in the segment-polarity signalling pathway. In fact, b-catenin/Armadillo turned out to be key mediators of the Wnt/Wingless pathways in vertebrates and invertebrates. (beta)-Catenin participates in both adhesion and signalling functions in a mutually exclusive manner; bound to cadherins at the plasma membrane or ʹunboundʹ in cytosolic or nuclear complexes. This model had placed (beta)-catenin at the crossroads between cadherin and Wnt signalling, leading to the dogma of inhibition of (beta)-catenin signalling by cadherins.