Colorectal carcinogenesis: Insights into the cell death and signal transduction pathways: A review

Figure 4 Wnt/β-catenin pathways. In the absence of Wnt, cytoplasmic β-catenin forms a complex with Axin (yellow), APC (blue), GSK3 (red), and CK1 (purple). Phosphorylated β-catenin undergoes ubiquitin-mediated proteosomal degradation. In the presence of Wnt, Wnt binds to the frizzled receptor, which in turn recruits the Axin complex. This disrupts Axin-mediated proteosomal degradation of β-catenin. Cytoplasmic β-catenin then travels to the nucleus and functions as a co-activator with TCF to activate Wnt-regulated gene expression. GSK: Glycogen synthase kinase; APC: Adenomatous polyposis coli; CK1: Casein kinase 1.