Effect of vitamin D depletion on Hes1 gene expression in old rats. mRNA expression of Hes1 in tibialis anterior of control and depleted rats was analyzed by using a RT2 Profiler Custom PCR Array following the manufacturer’s protocol. Hes1 mRNA in control and vitamin D depleted samples was normalized using expression of Tbp as a housekeeping gene and was relative to control group according to the 2-ΔΔCT method (n = 7 for control group and n = 9 for depleted group). The expression of Hes1 was significantly reduced after vitamin D depletion in old rats. Data presented are means ± SEM; *p < 0.05.