MIP-1α acts at the later stages of osteoclast formation.

Human bone marrow cultures were treated with hMIP-1α (200 pg/mL) for varying periods of time. hMIP-1α significantly increased OCL formation only when present during the last 2 weeks of the 3-week culture period. Results represent the mean ± SEM for quadruplicate determinations for a typical experiment. Similar results were seen in the 3 independent experiments. *P < .05 compared to media alone.