Figure 4. Exogenous addition of ADPribosyl cyclase augments, while NADase inhibits osteoclast formation.

Ficol-purified bone marrow cells were plated with either RANK-L and M-CSF alone, or with the addition of 2 to 60 mU Aplaysia ADPribosyl cyclase or 2 to 60 mU of snake venom NADase enzymes. The exogenous addition of ADPribosyl cyclase (Cyclase) augmented osteoclast formation with doses detectable at doses as low as 2 mU. In contrast, the addition of NADase inhibited osteoclast formation, with modest inhibition between 2 to 10 mU, and complete inhibition at 30 mU or greater. The depiction of the differences in enzymatic activity between the Cyclase and NADase is shown in the lower right corner.