KL and arteriosclerosis: In the kidney, α-Klotho plays a role of a coreceptor for fibroblast growth factor 23 (FGF23) associated with arteriosclerosis prevention [4] and is involved in phosphorus excretion [5], whereas soluble α-Klotho participates in the regulation of endothelial nitric oxidase synthase (eNOS) activity and calcium channel transient receptor potential vanilloid 5 (TRPV5) in calcium homeostasis [6].