Fig. 2

β-Carotene induces increases in intracellular ROS levels and caspase-3 activity, and decreases in Ku70/80 levels and Ku-DNA-binding activity in AGS cells. The cells were cultured with β-carotene (final concentration of 100 μM) for 12 h (a, b) or for various periods (0, 4, 8, 12 h) (c, d). a Intracellular ROS levels were determined by measuring DCF fluorescence with a fluorescence multi-well plate reader. The results are expressed as the mean ± SEM of four separate experiments. *p < 0.05 versus cells treated without β-carotene (none). b Caspase-3 activity was determined by measuring the cleavage of the fluorescent peptide substrate DEVDAFC. Caspase-3 activity in cells treated without β-carotene (none) was set at 100 %. The results are expressed as the mean ± SEM of four separate experiments. *p < 0.05 versus cells treated without β-carotene (none). c The levels of Ku70 and Ku80 in total cell lysates were determined with Western blot analysis. Actin served as a loading control. d Ku-DNA-binding activity in nuclear extracts was determined with EMSA