MYC-dependent osteogenic sarcoma cells are dependent on mitochondrial ROS for cell proliferation. Doxycycline (20 ng/mL) was added to MYC-dependent osteogenic sarcoma cells and incubated for 48 hours. (a) Mitochondrial ROS was assessed using oxidation of mitochondrial targeted roGFP2. N = 4 ± SEM * P<0.05 compared to without doxycycline. (b) Cytosolic ROS was assessed using oxidation of cytosolic roGFP2. N = 4 ± SEM. (c) Cells were treated with PEITC (0 to 100 μM) for 24 hours and cell death was measured. N = 4 ± SEM. (d) Cells were treated with BSO (0 to 100 uM) for 24 hours and cell death was measured. N = 4 ± SEM (e) Mitochondrial ROS as assessed by mito-roGFP2 in cells treated with control TPP (0.5 μM) or mitochondrial targeted vitamin E (MVE 0.5 μM). N = 6 ± SEM * P<0.05 compared to TPP control. (f) Cell proliferation was assessed upon treatment with TPP (1 μM) or MVE (0.5 or 1 μM) for 48 and 72 hours. N = 3 ± SEM * P<0.05 compared to 1 mM TPP control. (g) Cell death was assessed after 48 hours of treatment with TPP or MVE. N = 4 ± SEM * P<0.05 compared to 1 mM TPP control without doxycycline.