A loxP site was inserted in to intron 1 and an FRT site, a loxP site, a neomycin resistance gene cassette, and a second FRT-loxP site pair into intron 3. The neo cassette was removed through subsequent flp-mediated recombination. Floxed exons 2 and 3 were deleted through subsequent cre-mediated recombination. (J:265391)