In this study, we used three different FGF23 concentrations (1, 10, and 100 ng/mL), which were not only in line with those used by other groups but also reflected FGF23 levels measured in the serum of patients with hypophosphatemic rickets or other diseases characterized by high FGF23 levels [33–41]. Here, FGF23 is linked to hypophosphatemic rickets.