A: The tartrate-resistant acid phosphatase assay was performed according to the manufacturer's instructions on mouse serum samples from control, prevention, and treatment groups, using the Mouse TRAP™ Assay measuring TRACP-5b activity (Immunodiagnostic systems Inc.) (n = 10). There were no significant differences associated with huRANKL MAb administration. B: Serum calcium levels were measured using a calcium ion electrode 8 weeks after intra-tibial C4-2 injection in the control, prevention, and treatment groups. Serum calcium levels were significantly different between control and prevention animals (p = 0.012). Serum calcium levels were not significantly different between control and treatment animals (p = 0.9631).