Fig. 4. Cytochalasin B treatment of undisturbed RGM1 cells does not effect resealing. (a) Control RGM1 cells stained with TRITC-phalloidin. (b) Cytochalasin B (5 minutes, 3 µg/ml)-treated cells stained with TRITC-phalloidin. Note that, by comparison with the untreated cells in (a), there is a marked disruption of cortical and stress fiber F-actin staining in these cells. (c) Nearly complete closure of monolayer injury sites was observed 2 hours after scratching a cover slip in PBS. (d) Closure failure was observed when cytochalasin B (3 µg/ml, added 5 minutes before scratching) was added to the PBS. (e) Fixable FDx (M_r 10,000)-positive cells, which suffered and survived a plasma membrane disruption, line a control wound site created in the presence of this marker (10 mg/ml) added to PBS. (f) FDx-positive cells, in apparently equivalent density, line a wound site in a culture treated with cytochalasin. (g) Quantitation of the density cell survivors of PMD along scratch sites. Scratch-loading was performed in PBS containing FDx and no additive (Cont), 5 mM-EGTA (EGTA) or 5 µg/ml cytochalasin B added 5 minutes before monolayer injury (CyB), and the number of FDx-positive cells lining a 100 mm distance along scratch edges counted for each condition. The mean and s.d. of three separate experiments are shown. Comparison of the EGTA treated and control samples yielded P<0.05 (*) (Kruskal-Wallis test), and for cytochalasin and control samples P=0.51269 (**). Bars, 30 µm.