These mice possess loxP sites on either side of exon 2 of the targeted gene. Mice that are homozygous for this allele are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. When used in conjunction with a Cre recombinase-expressing strain, this strain is useful in generating tissue-specific mutants of the floxed allele, which is hypomorphic. The Jackson Laboratory 2024, used with permission.