Intracellular ROS evaluation of PO and VV protein extract-treated SW480 cells. SW480 cells were exposed to PO and VV protein extracts (100 μ g mL −1 ) for 24 h. Production of intracellular ROS was detected by flow cytometry using DCFH-DA. The intracellular fluorescence of DCF was measured with a Becton-Dickinson FACScan flow cytometer. Data in each panel represent the DCF fluorescence intensity within the cells. The values shown are the means ± SD ( n = 5–8 of individual experiments). * P