DXA measurements of bone parameters in WT, ERKO, BERKO, and DERKO mice (n = 6 for WT; n = 9 for ERKO; n = 6 for BERKO; and n = 5 for DERKO). The BMC (A), BMC/body weight (B), and BMC/length (C) of the whole skeleton (total), femur, spine, and cranium were measured by using DXA technique as described in Methods. Values are given as means ± SEM. Data at different ages first were analyzed by a two-way ANOVA, followed by Student–Newman–Keuls multiple range test. P values versus WT mice are indicated.