Klbfl mice have loxP sites flanking exon 1 of the klotho beta Klb gene. KLB is a co-receptor of fibroblast growth factor 21 (FGF21), a hormone produced by the liver that signals to the brain to regulate macronutrient intake, energy homeostasis, and water consumption. KLB is also a receptor for FGF15/19, a hormone that signals from small intestine to liver to regulate bile acid homeostasis. Mice that are homozygous for this allele are viable and fertile. When bred to mice that express tissue-specific Cre recombinase, resulting offspring will have exon 1, including the translation initiation sequence, removed in the cre-expressing tissues of the offspring.

Klbfl mice have loxP sites flanking exon 1 of the Klb gene. These mice are useful when studying nutrient regulation, metabolic homeostasis, and water consumption.