Figure 3. Serum markers and skeletal gene expression in Dmp1-PPRKO mice. (A) Serum calcium, phosphate, PTH and sclerostin in male control and Dmp1-PPRKO mice was measured by ELISA. PTH levels were normalized to 13-month-old control due to a high intra-assay variation (>9.8%). (B) Serum levels of bone formation (P1NP) and resorption marker (CTX) were also measured by ELISA. N = 7–19 per group. Data are presented as mean ± SEM. (C) Gene expression in marrow-removed long bones of male mice was analyzed with qPCR. N = 4–6 per group. Two-way ANOVA with Tukey’s post hoc test, unpaired Welch’s t test, or Mann-Whitney test was performed. *p < 0.05, **p < 0.01, ***p < 0.001. Each gene expression was relative to 3 housekeeping genes (Actb, B2m, and Gapdh), which were selected by GeNorm. Expression data are presented as mean ± SEM.