The allele was generated by inserting a Frt-PGKNeopA-Frt cassette followed by three copies of myc-tag sequences fused to the N terminus of the Tbr1-coding sequence, and two loxP sites flanked the first exon. This allele is a Tbr1 functional allele. The neo selection cassette was removed by FLP recombinase. (J:281028)