Heterozygous Kazntm1a(EUCOMM)Wtsi mice were mated with 129S4/SvJaeSor-Gt(ROSA)26Sortm1(FLP1)Dym/J mice (C57BL/6J; Jackson Laboratory, Bar Harbor, ME) to remove the FRT-En2-IRES-BGal-loxP-Neo-pA cassette from intron 4, leaving loxP sites flanking exon 5. (J:226589)