The targeting construct introduced at the exon 1 translation initiation site a loxP site, nucleosome localized GFP reporter gene with 4 polyadenylation sequences (H2B-GFP-4XpA), loxP site, FRT-flanked neomycin resistance cassette and 3 FLAG tags. Flp-mediated recombination removed the selection cassette. (J:212423)