Fig. 1. Possible mechanisms for -catenin-mediated cooperation between classical cadherins and the actin cytoskeleton. (A) A popular earlier model posited a quaternary complex comprising classical cadherins, ß-catenin, -catenin and cortical actin filaments. In this model, -catenin directly binds to both actin filaments and ß-catenin, thereby coupling stable actin filaments to the cadherin adhesion molecule. (B) The more complex current possibilities. -Catenin, acting in the cytosol or bound through ß-catenin to the cadherin molecular complex has the capacity to regulate the actin cytoskeleton by several mechanisms: binding directly to actin filaments, potentially thereby inhibiting Arp2/3-mediated actin nucleation; interacting with a range of actin regulators, including filament nucleators and binding proteins; and interacting with cell signalling pathways that can affect actin dynamics and organization. (C) The regions of -catenin responsible for association with some actin-binding proteins have been mapped.