Tbx2^{tm1.1(cre)Vmc}

Briefly, 5.9 kb of upstream and 2.2 kb of downstream Tbx2 129/SvJ genomic fragments were amplified by PCR and ligated to an Frt-flanked Cre-polyA-PGK-neo cassette replacing the first five codons of the Tbx2-coding region in exon 1. A diphteria toxin negative-selection cassette was placed at the 5' end of the targeting construct. Homologous recombination was performed in E14IB10 ES cells. The PGK-neo cassette in Tbx2CreNEO animals was removed subsequently by crossing with FlpE mice. Tbx2 expression is undetectable in homozygous embryos which show a similar hindlimb phenotype to that observed in Tbx2-deficient (Tbx2tm1Pa) embryos. (J:155719)