An FRT-flanked neomycin resistance cassette with a 5' loxP site was inserted upstream of exon 2. A second loxP site was inserted downstream of exon 5. Flp-mediated recombination removed the selection cassette and left exons 2 through 5 floxed. Cre-mediated recombination removed exons 2 through 5. (J:210950)