APC and adenoma: Other groups have observed that a single truncating mutation in Apc (as seen in Apc+/Min-FCCC mice) may increase Wnt signaling at the base of the nonneoplastic colon crypt; enhanced signaling may then drive an expansion of colon epithelial stem cells, increase cellular proliferation along the length of the crypt (27), and ultimately promote adenoma formation (30, 56).