A loxP site was inserted 300 nucleotides 5' of the initiation methionine codon in exon 1 and a floxed neomycin resistance gene as well as an EGFP gene were inserted in intron 2. Crossing to cre-deleter mice led to the excision of the the coding portion of exon 1 and exon 2 as well as the neo resistance gene. RT-PCR and Western blot analysis confirmed the absence of transcription and translation. The EGFP insert was non functional. (J:94941)