FIGURE 1.

The canonical Wnt signaling pathway is dependent on the activation of intracellular molecule β-catenin. In the absence of Wnt-binding Fz receptors, β-catenin is isolated into a protein, phosphorylated, and subsequently degraded by the destruction complex. Upon binding to the Fzl receptors and LRP5/6 co-receptors, the Wnt/β-catenin signaling pathways is activated while the degradation complex of β-catenin is inhibited, allowing the newly synthesized β-catenin to accumulate in the cytoplasm and transfer to the nucleus. Nuclear β-catenin can replace the transcription corepressors in TCF transcription factors and promote the activation of gene transcription programs.