The targeting vector is designed to insert a loxP site upstream of exon 8, and a FRT-flanked neomycin resistance cassette followed by a second loxP site downstream of exon 8. Exon 8 also contains a 952delT mutation that corresponds to the 967delT human mutation associated with autosomal dominant congenital stromal corneal dystrophy (CSCD). Flp-mediated recombination removed the FRT-flanked neo cassette and cre-mediated recombination removed exon 8.