The translation start codon, AUG, in exon 2 was replaced with a stop codon, UAG, and removed around 200 bp upstream of the putative transcriptional start site of promoter 2. This allele maintains expression from promoter 1 (P1), but not promoter 2 (P2). Cre-mediated recombination removed the flocked neomycin resistance cassette. (J:245723)