RAW 264.7 cell cultures treated with exogenous RANKL and MCSF showed a 9.9-fold increase of TRAP activity compared to controls without cytokine treatment. We found that the release of this osteoclast-associated enzyme was potently inhibited by our mAb-sCT conjugate (and by our unconjugated mAb alone), as compared to sCT alone (Fig. 7) . We measured a 5.47-fold decrease in TRAP activity after treatment with mAb-sCT conjugate. Also, the conjugate showed a 2.82-fold greater inhibition of TRAP compared to sCT treatment alone.