The targeting construct is designed to insert a creERT2 fusion gene (a Cre recombinase fused to a human estrogen receptor ligand binding domain) followed by an SV40 polyadenylation signal, and a FRT-flanked neomycin resistance (neo) cassette into exon 2 of the gene. Flp-mediated recombination removed the FRT-flanked neo cassette. (J:256199)