Serum markers of bone disease in the INA6 model of myeloma. Serum levels of human Dkk-1 (A), PYD (B), and TRAP (C) in engrafted and nonengrafted (controls) mice. Range (left) and mean with SD (right) are presented. Error bar represents SD for n = 5 samples per group. **P < .01, ***P < .005 with Student t test. Experiment was performed twice.