Effect of hemin, SFN, QUE and 3,4HPAA in MMP. 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, MMP was measured by fluorescence in (A) RKO; and (B) CCD841 cell supernatants. 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. The values with different letters indicate significant differences (p < 0.05) between bars (two-way ANOVA, Bonferroni post-test3,4HPAA, 3,4-dihydroxyphenylacetic acid; MMP, mitochondrial membrane potential; QUE, quercetin; SFN, sulforaphane; RFU, relative fluorescence unit.