Characterization of the MMLAL cells. A) Cells were seeded at an initial density of 1 × 106 cells/ml and allowed to grow with fresh medium change on every three days. The cells were stained by trypan blue and the number of viable cells measured by haemocytometer as indicated. B) Cell viability of was measured by MTT assay after treatment with different concentrations of bortezomib, and compared to the untreated control. Data were plotted by the average of three independent experiments ± standard deviations.