Fig. 2. Microtubule disassembly induces changes in the organization of cortical actin. LLC-Pk1 cells stably expressing GFP-actin are shown before and at various times after the addition of 33 µM nocodazole. (A-D) Contractile-ring formation and cytokinesis in a control cell (A) and in cells to which nocodazole was added either within 2 minutes of (B) or >2 minutes after (C,D) anaphase onset. In B, both contractile-ring assembly and cytokinesis fail, whereas in C and D, furrow formation and ingression proceed. Wave-like behavior of cortical actin is shown in the inset panels in B. Arrowheads mark wave-like behavior in B and C. In D, actin from distal regions of the cortex flows towards the equatorial region and contributes to the contractile ring; arrows mark the direction and region contributing to flow. Time is shown in minutes:seconds and is relative to the addition of nocodazole in B-C. Scale bars: 10 µm.