KL and osteoporosis: In 1997, Klotho was discovered as a transmembrane protein usually expressed in proximal and distal renal tubules, which was subsequently identified as an anti‐ageing factor and shown to exert inhibitory effects on insulin/insulin‐like growth factor‐1 signalling (Figure 1), oxygen free radicals and phosphate/calcium homoeostasis.31 Multiple ageing‐associated diseases develop in mice with genetic deficiency of Klotho, including osteoporosis, stroke and arteriosclerosis.