BMP-4 induces apoptosis in samples of purified primary myeloma cells.

Primary myeloma cells from patients 1 and 5 were stimulated with 50 ng/mL BMP-4 1 ng/mL IL-6, or both, as indicated, and annexin V–FITC and PI binding were measured by flow cytometry. Numbers represent the percentage of cells in the respective quadrants. Cells in the lower left quadrant were considered viable, in the lower right quadrant apoptotic, and in the upper quadrants dead.