Balancing cell adhesion and Wnt signaling, the key role of β-catenin

Controlled regulation of cell proliferation and differentiation is essential for embryonic development and requires the coordinated regulation of cell–cell adhesion and gene transcription. The armadillo repeat protein β-catenin is an important integrator of both processes. β-catenin acts in the Wnt signaling pathway, activating the transcription of crucial target genes responsible for cellular proliferation and differentiation. β-catenin also controls E-cadherin-mediated cell adhesion at the plasma membrane and mediates the interplay of adherens junction molecules with the actin cytoskeleton. Both functions of β-catenin are de-regulated in human malignancies, thereby leading both to the loss of cell–cell adhesion and to the increased transcription of Wnt target genes.