FIGURE 6.

Less Arp2/3 within lamellipodia of Toca-1 knockdown A431 cells. A, A431 vector, shRNA1, and shRNA2 cell lines were serum-starved and treated with EGF (100 ng/ml) for 5 min, prior to staining of F-actin and endogenous Arp2/3 (p34-Arc or Arc-C2 subunit) as described under “Experimental Procedures.” Representative confocal microscopy images for F-actin (green), p34-Arc (red), and a merged image are shown for control (a–c) and Toca-1 knockdown cells (d–i). The insets reflect a higher magnification of the boxed areas, and arrows indicate some examples of lamellipodia. Intensity profiles for green and red channels across a representative lamella (indicated by lines within insets) are shown on the right for each cell line. Scale bar, 30 μm. B, the graph depicts quantification of the relative p34-Arc staining intensity (relative units (RU)) within lamellipodia ± S.E. (error bars) (>30 cells analyzed) for Toca-1 knockdown cells relative to vector control cells, as described under “Experimental Procedures.” *, significant difference between Toca-1 knockdown and vector control cells based on paired Student's t test (p < 0.01).