Figure 4

Regulation of adherens junction and β-catenin stability. A, Localization of β-catenin at the adherens junction occurs in a complex with E-cadherin and α-catenin. β-catenin is also present in the β-catenin-destruction complex where it is being degraded in the absence of Wnt ligand. B, Growth factor (GF) as well as oncogene mediated activation of kinases can phosphorylate two conserved tyrosine residues in the N- or C-terminus of β-catenin, leading to a disruption of the adherens complex and formation of a nuclear β-catenin complex. Once in the nucleus, β-catenin can replace co-repressors from TCF/LEF and thereby form activating transcriptional complexes. Activation of Wnt results in the stabilization of β-catenin and its nuclear accumulation where Wnt target genes are turned on (see text for details).