A loxP site was inserted upstream of exon 4. A floxed cassette with a splice acceptor, IRES, and GFP reporter gene were inserted downstream of exon 4. Flp-mediated recombination removed the FRT-flanked neomycin resistance cassette previously located within the reporter cassette. Cre-mediated recombination removed exon 4 and the reporter cassette. (J:281818)