RedET recombineering was utilized to insert a cassette containing cre with a nuclear localization signal (NLS), a V5 epitope tag and the SV40 polyadenylation site, into a BAC clone (RP23-109K12) containing the advillin (Avil) locus. Correctly targeted clones were purified and injected into pronuclei of B6D2F1/N oocytes or prepared for intracytoplasmic sperm injection (ICSI). Both methods produced transgenic offspring. The line used for detailed analysis had 5 copies of the cre transgene.