SK2-specific shRNA inhibited cell proliferation and induced caspase 3 activation in myeloma cells. OPM1 cells were transduced with lentiviruses expressing SK2-shRNA-DsRFP or control shRNA-DsRFP for 4 hours. The cells were then washed and grew in regular culture medium for an additional 48 hours. (A) Fluorescent microscopy image showing DsRFP expression. (B) Expression of SK2 mRNA in SK2-shRNA- or control shRNA-transduced OPM1 cells. (C) Cell proliferation by MTT assay. Cell proliferation was measured using MTT assay at 0 hours and 48 hours after transduction. (D) Cell proliferation by flow cytometry. OPM1 cells transduced with SK2-shRNA or control shRNA were stained with CellTrace Violet Cell Proliferation dye and allowed to proliferate for 7 days. The dye fluorescence intensity was measured by flow cytometry. (E) Activation of caspase 3. OPM1 cells were transduced with SK2-shRNA viruses or control shRNA viruses. Forty-eight hours later, the cells were stained with Live/Dead Fixable cell dye, then fixed and permeabilized, and stained with caspase-3 antibody. Caspase 3 intensity was gated on the live cell population. Data were representative of 4 separate experiments.