Serum levels of (A) blood urea nitrogen (BUN), (B) calcium (Ca), (C) phosphate (P), (D) parathyroid hormone (PTH), and (E) FGF23 in WT mice, osteocyte-specific 1αOHase–/– KO mice (Oct), and global 1αOHase–/– KO mice (Global) at 13 weeks of age. “Ad” indicates treatment with adenine. Global 1αOHase–/– KO mice remained on a high calcium diet during the course of the experiments. Data are the mean ± SEM (n = 6–8 mice of each genotype). ****P ≤ 0.0001,***P ≤ 0.001, **P ≤ 0.01, *P ≤ 0.05 compared with mice of the same genotype on a non-adenine–containing diet, and ◊◊◊P ≤ 0.001, ◊◊P ≤ 0.01 compared with WT mice, determined by ANOVA with Bonferroni multiple comparison test.