Cofilin is activated upon H₂O₂ stimulation in PtK1 cells.

<p>(A) Immunolocalization of phosphorylated cofilin (P-cofilin, green) and F-actin phalloidin staining (red) in starved PtK1 cells treated with 500 µM H₂O₂ for the indicated times. The scale bar is 10 µm. Red lines highlight the leading edge of the cells. (B and C) Fluorescence intensity of P-cofilin (B) and F-actin (C) in cells treated with 500 µM H₂O₂, measured from the cell edge (0 µm) into the cell center (10 µm). (D) P-cofilin/F-actin fluorescence intensity ratio in cells treated with 500 µM H₂O₂, measured from the cell edge (0 µm) into the cell center (10 µm). In (B)–(D), the data shown represent one experiment and are averaged from at least 18 cells for each condition. The experiment was repeated three times with similar results (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041342#pone.0041342.s002" target="_blank">Figure S2A</a>). (E) Cell lysates from starved PtK1 cells treated with 500 µM H₂O₂ alone or in combination with ROS scavenger (5 mM) for 0-15-30-45-60 min were immunoblotted with antibodies against P-cofilin and cofilin. In (F), the graph represents the averaged P-cofilin/cofilin values. Data are from six and three independent experiments for H₂O₂ and H₂O₂+ROS scavenger, respectively. Error bars represent s.e.m. ***, p<0.001 compared to 0 min H₂O₂ and **, p<0.01 compared to 45–60 min H₂O₂.