The targeting vector was constructed containing a floxed exon 3 of the Lhx4 gene, an FRT-flanked En2 splicing acceptor-IRES-tdTomatopGK-Neo (tdT-Neo) cassette into the intron upstream of the exon 3 of the Lhx4. FRT-flanked En2 splicing acceptor-IRES-tdTomatopGK-Neo (tdT-Neo) cassette was removed by FLPe recombinase leaving loxP flanked exon 3. The loxP flanked exon 3 was then removed by cre recombinase removing Exon 3 and resulting in a frameshift. This is a null allele. (J:303030)