Enriched bone marrow plasma cells isolated from patients with (A) active (relapsing) MM, (D) nonactive (plateau) MM, and (G) MGUS stained with May-Grünwald-Giemsa. Expression of (B) MMP-2 and (C) MMP-9 mRNA by the plasma cells of the active MM patient; (E) MMP-2 and (F) MMP-9 mRNA by those of the nonactive MM patient; (H) MMP-2 mRNA by those of the MGUS patient; (I) MMP-2 mRNA by a control subject (a patient with pernicious anemia). Note the weaker MMP-2 expression in the nonactive MM patient, a weak expression in the MGUS patient, and no expression in the control. Bar, 22 μm in (A), (D), (G); 16 μm in (B), (C), (E), (F), (H), and (I).