Ectopic expression of miR-128b and miR-221 restores glucocorticoid sensitivity to RS4;11 cells. (A) Sorted GFP⁺ control– (termed MDH), let7b–, miR-221–, or miR-128b–transduced cells are treated (DEX⁺) or not (DEX⁻) with 10 μM DEX for 40 hours, followed by FACS analysis. The percentage of viable cells is determined by dividing the number of annexin V⁻ GFP⁺ cells by the number of total cells analyzed (n = 3) **P < .05. (B) The absolute cell number of annexin V⁻ GFP⁺ cells before treatment (left panel), without (middle panel), or with 10 μM DEX treatment (right panel) for 40 hours (n = 3). **P < .05. (C) Representative FACS profiles of the sorted control–, let7b–, miR-128b–, or miR-221–transduced RS4;11 cells with (DEX⁺) or without (DEX⁻) treatment with 10 μM DEX. The GFP⁻ cells in all panels represent dead cells in which GFP has been released; the majority are positive for annexin V staining (supplemental Figure 1). The percentage of viable cells is determined by dividing the number of annexin V⁻ GFP⁺ cells by the number of total cells analyzed. (D) Sorted GFP⁺ miR-128b–, miR-221–, or control–transduced (MDH and let7b) cells are treated with different concentrations of DEX for 40 hours, followed by FACS analysis. GFP⁺ cells are assessed for viability by annexin V staining in the same manner as in panel A. The vertical axis shows the percentage of the number of GFP⁺ annexin V⁻ cells after DEX treatment relative to the number of GFP⁺annexin V⁻ cells without DEX treatment. The 50% inhibitory concentration values for DEX killing of cells expressing let7b, MDH, miR-221, and miR-128b are 367, 31.9, 0.6, and 0.00033 μM, respectively. *P < .05, let7b vs miR-128b. **P < .05, let7b vs miR-221 and miR-128b.