A, 2-DG enhances activation of the mitochondrial apoptotic pathway by TRAIL. Upper panel: Mel-RM and MM200 cells treated with the combination of 2-DG (10 μM) and TRAIL (200 ng/ml) for 16 hours were subjected to measurement of ΔΨm by JC-1 staining in flow cytometry. The number in each left bottom quadrant represents the percentage of cells with reduction in ΔΨm. Lower panel: Cytosolic and mitochondrial fractions of Mel-RM and MM200 cells treated with the combination of 2-DG (10 μM) and TRAIL (200 ng/ml) for 16 hours were subjected to Western blot analysis. Western blot analysis of COX IV or β-actin levels was included to show relative purity of the mitochondrial or cytosolic fractions. B, A summary of studies of the effect of 2-DG on TRAIL-induced apoptosis in a panel of melanoma cell lines and a melanocyte line. Cells were treated with 2-DG (10 μM) and TRAIL (200 ng/ml) for 24 hours before apoptosis was measured by the propidium iodide method using flow cytometry. The data shown are either the mean ± SE (A, B, & F), or representative (C, D, & E), of three individual experiments.