MMP-2 and MMP-9 secretion by bone marrow plasma cells. The patient with nonactive MM was in the plateau phase; the patient with active MM was at relapse; the control was a patient affected with anemia due to iron deficiency. (A) SDS-PAGE gelatin zymography of plasma cell CM samples. Note the white bands against a dark background with an apparent molecular weight of 62 kD and 88 kD, corresponding to the gelatinolytic regions of activated (cleaved) MMP-2 and MMP-9, respectively. Measurement of the intensity of the bands, as evaluated by computerized image analysis, is shown in (B). The assay was performed in duplicate for each CM. Reproducibility was ≤±20% of the mean intensity value. The lowest (third) band in the lane of the active MM patient represents the 54-kD cleaved form of MMP-2,2 which is sometimes present in the CM of both nonactive and active MM patients, but is not correlated with disease activity.