The targeting construct was designed to insert a loxP site upstream of exon 1 and an FRT-flanked neomycin cassette followed by a loxP site downstream of exon 1. The loxP-flanked region includes the DM domain, a zinc finger-like DNA-binding motif, as well as the transcription start site and part of the first intron. Flp-mediated recombination removed the FRT-flanked neo cassette. (J:65541)