Interestingly, HypoC associated with hyperphosphatemia induced a 0.4 ± 0.08-fold decrease in FNDC5 mRNA expression (Fig. 4C), and HypoC in combination with 0.5 or 2 mM PO4 concentration induced a 0.5 ± 0.1 and 0.6 ± 0.05-fold decrease in FNDC5 mRNA expression compared to control, suggesting a detrimental effect on muscle cells. Here, FNDC5 is linked to hyperphosphatemia.