Effect of different ratios of linoleic acid (LA) to α-linoleic acid (ALA) on PCB77-induced oxidative stress. Cultures were incubated in media supplemented with 20 μM fatty acids, either all LA, all ALA, or different ratios of LA to ALA (R2:1, R1:1, R1:2) for 24 h. Some cultures were first pre-treated with these different ratios of fatty acids for 18 h, followed by coexposure to 3.4 μM PCB77 for additional 6 h. C = vehicle control. Values are means ± SEM (n = 3). Statistical comparisons of the two experimental settings (without and with added PCB77) are indicated by small and capital letters. Different letters represent significant differences among the treatment groups.