Mice homozygous for this conditional (floxed) allele possess loxP sites flanking exon 8 of the targeted gene and are viable and fertile, with circadian behavioral rhythms indistinguishable from wildtype littermates. When bred to mice that express Cre recombinase, the resulting offspring will have the exon encoding the BMAL1 (formerly ARNTL) basic helix-loop-helix (bHLH) domain deleted in the cre-expressing tissue(s). These Bmal1-floxed mutant mice may be useful in generating conditional mutations (whole-mouse or tissue-specific) to study the role of circadian clock/circadian rhythm in physiological and behavioral regulation. The Jackson Laboratory 2024, used with permission.