ZEB1 and ZEB2 depletion by shRNAs in NMuMG cells attenuates F-actin stress fibers. Cells were treated as indicated with 100 pM TGF-β1 for 48 hours followed by an additional 72 hour incubation with a lentivirus encoding pLKO.1 (a control shRNA) or lentiviruses encoding shRNAs against ZEB1 and ZEB2, with 1 μM Y27632 or 10 μM SP600125 added during the last 24 hour incubation with the shRNAs. F-actin was visualized by phalloidin. Cells were viewed at a 400× magnification. White arrows point to stress fibers.