MSTN and hypophosphatemic rickets: Although such treatments do not affect cell proliferation at the experimental tested condition, it induces a decrease in MRFs, desmin, irisin, myostatin, MHC, FGFRs, and α-KLOTHO gene expression during differentiation, indicating the possible involvement of FGF23 in muscular dysfunction characterizing hypophosphatemic rickets and the possible presence of negative feedback providing protection against high FGF23 levels.