Using BAC recombineering technology, the Cre sequence was inserted downstream of ATG codon in mouse Csn2 gene within the BAC clone RP23-218H23. After removal of selection cassette, the final BAC was injected into fertilized BALB/c oocytes. Line numbers were not indicated. The pound symbol (#) is used when no line is specified and/or lines are pooled. (J:265285)