A cre/ERT2 sequence was inserted by homologous recombination into the first exon of the Nr2e1 (Tlx) locus in BAC clone RP24-344A4. The BAC was linearized and injected into pronuclei of fertilized oocytes. Twenty-three founders were obtained and screened for inducible cre activity by crossing to ROSA-EYFP reporter mice. No line numbers were provided for mouse lines used to generate the data.