Effect of hemin, SFN, QUE and 3,4HPAA in ROS levels. Cells were incubated with vehicle (0.4% DMSO), 1 μM SFN, 10 μM QUE or 2.6 μM 3,4HPAA in the absence or presence of 10 μM hemin. After 72 h, DCF oxidation was measured by fluorescence in (A) RKO cells; and (B) CCD841 cells; as well as MitoSoxTM Red oxidation in (C) RKO cells; and (D) CCD841 cells. The results were expressed as RFU/mg of protein. Values are expressed as mean ± SEM, from three independent culture preparations. For all bars with the same letter, the difference between the means is not statistically significant. Values with different letters indicate significant differences (p < 0.05) between bars (two-way ANOVA, Bonferroni post-test). 3,4HPAA, 3,4-dihydroxyphenylacetic acid; DCF, dichlorofluorescein; QUE, quercetin; SFN, sulforaphane; RFU, relative fluorescence unit.