KL and cardiac hypertrophy: Bianchi et al. found that FGF23 drove expression of matrix metalloprotein-13 and type X collagen alpha 1 chain in human osteoarthritic chondrocytes in a Klotho-independent manner [25], while Faul et al. demonstrated that FGF23 induced myocardial hypertrophy by activation of the calcineurin-NFAT signaling pathway [10].