Exons 4-5 were flanked by loxP sites and a FRT-flanked neomycin resistance cassette was inserted upstream of exon 4. Flpe-mediated recombination removed the neomycin cassette. Cre-mediated recombination led to an in-frame deletion of exon 4 and 5, removing both EGF domains. Sequencing of cDNA indicates correct splicing from exon 3 to 6. (J:249238)