A gene trap targeting vector containing an FRT site, attP site, neomycin resistance cassette, attB site, EGFP, FRT site, and loxP flanked exon 2 was inserted into intron 1 via homologous recombination. FLP-mediated recombination removed the FRT flanked neomycin cassette and EGFP gene, leaving loxP flanked exon 2 (J:225909)