Once upon a time there was β‐catenin in cadherin‐mediated signalling

β‐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 β‐catenin, armadillo , was independently identified downstream of w ingless in the segment‐polarity signalling pathway. In fact, β‐catenin/Armadillo turned out to be key mediators of the Wnt/Wingless pathways in vertebrates and invertebrates. β‐Catenin participates in both adhesion and signalling functions in a mutually exclusive manner; bound to cadherins at the plasma membrane or ‘unbound’ in cytosolic or nuclear complexes. This model had placed β‐catenin at the crossroads between cadherin and Wnt signalling, leading to the dogma of inhibition of β‐catenin signalling by cadherins.