A loxP site was inserted into intron 1 (185 bp downstream of the ATG start codon) and a loxP-flanked neomycin cassette was inserted into intron 2. Cre-mediated recombination removed the neomycin cassette generating a conditional allele. The coding sequence is disrupted by two short introns (1 and 2) and it is this middle intron that is floxed. (J:324922)