Figure 1.

Canonical Wnt signaling pathway. In the absence of signal, action of the destruction complex (CKIα, GSK-3β, APC, Axin) creates a hyperphosphorylated β-catenin, which is a target for ubiqitination and degradation by the proteosome. Binding of Wnt ligand to a Frizzled/LRP-5/6 receptor complex leads to stabilization of hypophosphorylated β-catenin, which interacts with TCF/LEF proteins in the nucleus to activate transcription. In a canonical pathway, CKIα, GSK-3β, APC, and Axin act as negative regulators and all other components act positively. Abbreviations: APC = adenomatous polyposis coli, CK = casein kinase, GSK = glycogen synthase kinase, Fzd = Frizzled-Rezeptor, LRP = low-density-lipoprotein receptor related protein, Tcf/Lef = T cell-specific transcription factor/lymphoid enhancer-binding factor.