MLN4924-resistant K562 (R-K562_MLN) leukemia cells show decreased sensitivity to MLN4924, but not all chemotherapeutics.

<p><b>A</b>) Cells (5×10³ cells/well) were seeded in 96-well plates and treated with increasing concentrations of MLN4924 for 72 hours. After treatment, cell growth and viability were determined by the CellTiter-Glo luminescence assay. Values shown are the mean percentage ± SD of viable cells relative to controls. <b>B</b>) Cells (1×10⁵/ml) were plated in 6-well plates. After incubation, cells were stained with trypan blue and counted at the time points indicated. R-K562_MLN cells were incubated in the presence or absence of 250 nM MLN4924 as indicated. Values shown represent the means ± SD of viable cells. <b>C</b>) Cells (5×10³/well) were seeded in 96-well plates and treated with increasing concentrations of MLN4924 for 72 hours. After incubation, cell viability was assessed by the CellTiter Glo assay. Values shown represent the mean percentage ± SD of viable cells relative to vehicle controls. R-K562_MLN-5W, R-K562_MLN cells that were maintained in MLN4924-free medium for 5 weeks. <b>D</b>) Cells (5×10³/well) were plated in 96-well plates and treated with increasing concentrations of chemotherapeutic drugs as indicated for 72 hours. Cell growth and viability was assessed by the MTS assay. Values shown represent the mean percentage ± SD of viable cells relative to vehicle controls.