Effect of vitamin D depletion on Delta-1 transcript levels and protein expression in old rats. (A) mRNA expression of Delta-1 in tibialis anterior of control and depleted rats was analyzed using a RT2 Profiler Custom PCR Array following the manufacturer’s protocol. Delta-1 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). Delta-1 mRNA level was reduced in the TA of vitamin D-depleted rats compared to controls. Data presented are means ± SEM; *p < 0.05. (B) Protein expression of Delta-1 was analyzed in tibialis anterior by western blotting and quantified using Multi Gauge V3.2 software. Expression of the total amount of p38 was used to normalize protein loading between samples (n = 7 for control group and n = 9 for depleted group). Delta-1 protein expression remained unchanged between the two groups. A.U = arbitrary units. Data presented are means ± SEM; *p < 0.05.