APC and colorectal cancer: Constitutive activation of the Wnt pathway occurs in the majority of colorectal cancer (CRC) and is caused mainly by mutations in the genes encoding tumor suppressor adenomatous polyposis coli (APC) (~80% of cases), β-catenin (~4.7%), the nuclear mediator of Wnt signaling TCF4 (~4.1%) or ubiquitin ligase F-box/WD repeat-containing protein 7 (FBXW7) (~10.4%)51.