Cytohesin-1 is not involved in the formation of membrane protrusions. Microscopic visualization of F-actin by the use of Cy3-phalloidin shows that the formation of membrane protrusions in mature Mo-DCs is not influenced by RNAi of cytohesin-1, compared with control cells (A). RNAi of RhoA also shows the same unaltered phenotype (B), whereas RNAi of Rac1 results in strong deficiencies in the formation of membrane protrusions (C). Quantification of membrane protrusions shows that after RNAi of cytohesin-1 respective RhoA 70% of all mature Mo-DCs have lamellipodia and do not differ from control cells (A,B). In contrast, RNAi of Rac reduces formation of lamellipodia approximately 50% (C). Bars represent 5 μm. In each individual experiment, 200 mature DCs were counted. Each single experiment was performed in duplicate. Error bars indicate ± SD. *P < .05. Each experiment was repeated at least 3 times independently.