Homologous recombination in bacteria was used to modify a 235Kb BAC RP24-384G1 containing 137 Kb upstream and 80 Kb downstream of the Lhx6 gene. An icre (improved cre) coding sequence was fused to the ATG of Lhx6 in exon 1 using a PCR-based approach. An SV40 polyA was inserted downstream of iCre. The construct was designed to delete the coding sequence of exon 1, as well as the first 80 bp from the first intron. Mice were generated by pronuclear injection of the construct into fertilized oocytes. No line number is given.