A loxP site and EcoRI siter were inserted 200 bp upstream of the transcription initiation site and a loxP site, EcoRI site, and FRT flanked neo cassette were inserted36 bp downstream of the stop codon via homologous recombination. Flp mediated recombination removed the neo cassette. Cre mediated recombination removed exons 1 and 2. (J:175781)