Leukocyte migrating (IMAGE) Institute of Science and Technology Austria Caption Illustration of a leukocyte migrating without transmembrane force-coupling in a smooth and bumpy road (cytoplasm in grey, nucleus in blue, actin cytoskeleton in red). The retrograde actin flow is shown by the red arrows in the left panel: in both cases, fast retrograde flow is generated from the front of the cell to the back. However, the flow only generates the necessary force that pushes on the channel when there are bumps, and the cell can move forward (right panel, bottom). Credit © Anne Reversat Usage Restrictions © Anne Reversat License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.