Fig. 7. A model for stimulated protrusion. Upon EGF stimulation, cofilin severing initiates a burst in free barbed ends. Polymerization at these barbed ends leads to the generation of ATP-actin-rich filaments at the leading edge. These filaments promote the nucleation and branching activity of the Arp2/3 complex, leading to the formation of a dense actin network adjacent to the plasma membrane, which facilitates cell protrusion.