Blockade of NF-κB activation enhances proapoptotic effects of standard chemotherapy. (A,D) REH, (B) RS4;11, and (C) OCI-AML3 cells were cultured alone (monoculture) or cocultured with BM-MSCs as indicated in Methods. Monocultured and cocultured cells were treated for 72 hours with either (A-B) VCR or (C-D) Doxo as monotherapy or in combination with one of the IKKβ inhibitors (A-C) MLN120B (MLN) or (D) CDDO-Me. The percentage of apoptotic cells (annexinV⁺/DAPI⁺) was assessed by flow cytometry using annexin V⁺/DAPI⁺ staining and counting beads. Data for the absolute number of viable cells are shown in supplemental Figure 5. Results are expressed as the mean of the percentage of annexin V⁺/DAPI⁺ (±SEM) of 3 independent experiments. *Statistically significant difference at P ≤ .05. AnnV, annexinV.