PGE₂ decreases apoptosis, increases Survivin expression, and decreases active caspase-3 in SKL cells. (A) Lin^neg bone marrow cells were treated with dmPGE₂ or vehicle and cultured in media supplemented with 2% FBS without growth factors for 24 hours to induce apoptosis. Cultured cells were stained for SKL and SLAM and PE-anti–active caspase-3 and/or FITC–annexin-V and the proportion of SKL or SLAM SKL cells undergoing apoptosis was determined by FACS. (Inset) dose-response analysis of the effects of dmPGE₂ on SKL cell apoptosis. (B) Fold increase in intracellular Survivin levels (mean fluorescence intensity [MFI]) in control and dmPGE₂-pulsed murine SKL and human CD34⁺ cells 24 hours after treatment; data are mean plus or minus SEM from 3 experiments; n = 3 mice/group, each assayed individually, or 3 separate cord blood samples. (C) Evaluation of intracellular Survivin and active caspase-3 levels (MFI) in SKL cells 24, 48, and 72 hours after treatment with dmPGE_2. Data are expressed as mean plus or minus SEM for 3 experiments; n = 3-6 mice/group, each assayed individually (*P < .05).