In vitro branched actin networks have been shown to generate a pushing force. In vivo these networks have been identified at different subcellular locations to drive membrane protrusion and remodeling during intracellular traffic. Here we will discuss the integration of positive and negative regulation of membrane protrusions and how it impacts the essential parameters of cell migration. Surprisingly we found that the signaling pathway that generates branched actin at membrane protrusions, Rac-WAVE-Arpin, also controls cell cycle progression.
In fact, this signaling pathway has all the expected properties of a cell cycle checkpoint. It is required in normal cells but this requirement is lost in cancer cells. The branched actin network of membrane protrusions integrates growth factor stimulation with mechanotransduction of cell adhesion to instruct the cell that its environment is permissive for migration and cell cycle progression.