A single nucleotide G to A substitution located 181 bp downstream of Zeb1 exon 1 and 12 bp downstream of exon 1 of the predicted gene Gm10125, a loxP site, and IRES-lacZ cassette, and a floxed inverted pgk-neo cassette were inserted via homologous recombination. Cre mediated recombination removed the IRES-lacZ and pgk-neo cassettes. This mutation is designed to duplicate the one found in Zeb1Tw mice (J:177274)