Fig. 3.

In osteoclasts deficient in CD200, the activation of signaling molecules downstream of RANK is suppressed. Bone marrow macrophages isolated from CD200-deficient, and wild-type mice were cultured in the presence of M-CSF (5 ng/ml) for 12–18 h. Nonadherent cells were further cultured for 2 days in 24-well dishes, starved for 2 h, and then stimulated with 50 ng/ml RANKL for the indicated times. Cells were subjected to Western blot analysis with antibodies directed against the indicated antigens. The activation, by phosphorylation, of IκB and JNK was less extensive in cells that lacked CD200 than in wild-type cells. This experiment was repeated three times with similar results.