Mouse BAC bmq-279H8 was modified to incorporate a cre/ERT2 with its own translational start site and polyA signal followed by an FRT-flanked kanamycin/neomycin cassette targeted to exon 1 of the Tbx6 gene. Flp-mediated recombination removed the FRT-flanked kan/neo cassette. Founder line 1Pa exhibited high levels of expression, and best recapitulated Tbx6 expression both temporally and spatially. (J:244767)