The primary mechanism leading to hyper-activation of Wnt signaling in cancer is loss of function (LoF) in APC, an event that is commonly observed in hereditary (familial adenomatous polyposis) and sporadic colorectal carcinomas (CRC) (Nishisho et al., 1991; Cottrell et al., 1992; Powell et al., 1992; Rowan et al., 2000). The gene discussed is APC; the disease is colorectal carcinoma.