Figure 5.

Depletion of Rac1 effectors rescues the cytokinesis defect of cells expressing a hydrolysis-defective Rac1 mutant. HeLa cells expressing inducible EGFP-Rac1^Q61L were transfected with siRNA duplexes targeting CYK4, ECT2, Rac1-specific effectors, Cdc42, a nonsilencing control (siControl), or Myh9, which was a protein binding nonspecifically to Sepharose beads in Rho GTPase pull-downs. Rac1^Q61L expression was induced for 48 h, and the cells were fixed and then stained with phalloidin to detect actin or DAPI to detect DNA. Rac1 was directly visualized by EGFP fluorescence. Binucleate cells are marked by asterisks. The number of binucleate cells was counted for each condition and plotted as in the bar graph. Error bars indicate the standard deviation from the means (n = 3). The dotted line indicates the extent of cytokinesis failure. Bars, 10 µm.