Fig. 1

The Wnt/β-catenin signaling pathway. a When Wnt proteins bind to LRP5/6 and FZD, the phosphorylation and degradation of β-catenin is blocked, resulting in stabilization, accumulation and nuclear translocation of β-catenin and subsequent activation of the pathway. b When Wnt binding to receptors is blocked by Wnt antagonist Dkk1, SOST and sFRP, β-catenin is phosphorylated by Ck1 and GSK3β, and subsequently degraded by the 26S proteasome. Wnt receptor Fzd and Wnt co-receptor LRP5/6 are positively regulated by Rspo proteins and their receptors LGR4, LGR5 and LGR6, and negatively regulated by E3 ubiquitin ligases RNF43 and ZNRF3 at the cell surface