The targeting construct introduced downstream of the translation stop site a loxP site, IRES, neomycin resistance cassette, polyadenylation sequence, loxP site, IRES sequence, and FLAG-tagged mouse Ctnnb1 cDNA lacking the N-terminal domain amino acids 1-131. Cre-mediated recombination removed the selection/STOP cassette and allowed for expression of the hypomorphic inserted sequence to mimic human sporadic colon cancer. (J:226549)