A loxP site was inserted downstream of exon 2. An FRT-flanked neomycin resistance cassette with a 3' loxP site and a EGFP with a splice acceptor was inserted downstream of exon 2. Flp-mediated recombination removed the neomycin resistance cassette. Cre-mediated recombination removed exon 2 and left the EGFP intact. (J:201118)