SIRT1 and hyperinsulinemic hypoglycemia, familial, 4: To determine whether the correction of 1,25(OH)2D deficiency-induced sarcopenia by Sirt1 overexpression in MSCs is related to inhibition of increased skeletal muscle SASP caused by 1,25(OH)2D deficiency, we collected tibialis anterior muscle from 2-month-old mice of the three genotypes and used p65 immunofluorescence staining and Western blots to compare changes in skeletal muscle cell senescence and SASP-related markers between genotypes.