Relationship between bone marrow neovascularization and bone marrow plasma cell angiogenic activity. For each patient, bone marrow microvessel area was measured and plotted against the microvessel area measured in the CAM-sponge assay after loading of the CM of his/her plasma cells isolated close to the biopsy site. Each symbol (bold square, active MM; triangle, nonactive MM; circle, MGUS) corresponds to one patient. Significance of the regression analysis was calculated by the Pearson (r) test.