A targeting vector was generated by recombineering of a 129S5 BAC to contain an IRES-cre-Frt-Neo-Frt sequence. Homologous recombination in AB2.2 ES cells inserted the IRES-cre into the 3' untranslated region of Dppa3. Germline chimeras were bred to 129S5 females to generated heterozygotes. (J:175778)