A targeting construct was designed to replace part of exon1 and intron 1 of the gene with a codon optimized Cre recombinase gene (iCre) followed by an internal ribosome entry site (IRES), an enhanced green fluorescent protein (EGFP), a polyadenylation site, and a frt-flanked neomycin/kanamycin resistance (neo/kan) cassette. (J:211105)