The Wnt-TCF (canonical Wnt) signaling pathway is initiated by the binding of a Wnt ligand to a frizzled family receptor on the cell surface. In the absence of a Wnt ligand, cytoplasmic levels of β-catenin (arm), the transcriptional effector of the pathway, are kept low through its constitutive degradation. Activation of the pathway leads to the inhibition of cytoplasmic β-catenin (arm) degradation and its subsequent accumulation in the nucleus, where it regulates the transcription of target genes. (Adapted from FBrf0218499 and FBrf0223299).