FIGURE 4:

Distinct patterns of cortical actin dynamics in anterior and posterior regions during cell migration. Using GFP–α-actinin as a marker for the ventral actin cytoskeleton, we observed distinct patterns of cortical dynamics in different regions (all movements analyzed as kymographs): stationary or slow forward transport in the anterior region (A; line indicates the extension of leading edge), compression in the region near the nucleus (B; N marks the nuclear region), and stretching and retraction at the tail (B, C). Structures at tip of the tail are stationary before tail retraction (B, bottom) but undergo rapid forward movement during tail retraction (C; the line indicates tail retraction). Inhibiting myosin II by either blebbistatin or Y-27632 does not significantly affect cortical dynamics in the anterior region or the region just behind the nucleus (D; near the top edge). The only effect of blebbistatin on cortical dynamics is to inhibit the surge of posterior structures due to tail retraction. Posterior structures become increasingly stretched as the cell migrates forward (E). Numbers indicate time in minutes. Bar, 10 μm.