Figure 1.

Key components of the canonical Wnt/β-catenin signaling pathway. Complexes formed by a Wnt ligand, Frizzled receptor protein and LRP5 or LRP6 initiate signaling within the cytoplasm. The signal acts via Dishevelled (Dvl) and Axin to inhibit the β-catenin destruction complex and thus increase the stabilization of β-catenin (β-cat), which then accumulates in the cytosol and nucleus. In the nucleus, β-catenin forms a complex with TCF proteins that activates the transcription of specific target genes. For simplicity, Dvl and Axin are shown as part of the β-catenin destruction complex, but each protein can also be found associated with the receptor complex. Components shown shaded in gray have an inhibitory effect on downstream signaling in the nucleus. The nomenclature used is as for mammalian cells (see Table 1 for the nomenclature of equivalent components in Drosophila). APC, the adenomatous polyposis coli protein; GSK3, glycogen synthase kinase 3.