<p>Modified Boyden chamber assays on collagen-I coated transwells were performed with <b>A)</b> HPDE or <b>C)</b> Colo357 cells treated either alone or in combination with 50 μM tBHQ, 10 μM SFN or 10 ng/mL TGF-β1, or left untreated for 24h. Data are expressed as percentage of invaded cells and represent the mean ± SD from eight independent experiments, *p<0.05 (+tBHQ and +SFN versus–tBHQ and–SFN, respectively). Boyden assays were also conducted with <b>B)</b> HPDE cells or <b>D)</b> Colo357 cells subject to Nrf2 or control siRNA treatment for 48h (westernblot verification shown in Figs. A and B in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132978#pone.0132978.s002" target="_blank">S2 File</a>) prior to further treatments with 50 μM tBHQ and/or 10 ng/mL TGF-β1. Data are expressed as percentage of invaded cells and represent the mean ± SD from six independent experiments, *p<0.05 (treated versus untreated).</p