Antagonism between Ena/VASP proteins and actin filament capping regulates fibroblast motility Bear, J.E., Svitkina, T.M., Krause,M., Schafer, D.A., Loureiro, J.J., Strasser, G.A., Maly, I.V., Chaga, O.Y., Cooper, J.A., Borisy, G.G., and Gertler, F.B. Cell, 109:509-521

Cell motility requires lamellipodial protrusion, a process driven by actin polymerization. Ena/VASP proteins accumulate in protruding lamellipodia and promote the rapid actin-driven motility of the pathogen Listeria. In contrast, Ena/VASP negatively regulate cell translocation. To resolve this paradox, we analyzed the function of Ena/VASP during lamellipodial protrusion. Ena/VASP-deficient lamellipodia protruded slower but more persistently, consistent with their increased cell translocation rates. Actin networks in Ena/VASP-deficient lamellipodia contained shorter, more highly branched filaments compared to controls. Lamellipodia with excess Ena/VASP contained longer, less branched filaments. In vitro, Ena/VASP promoted actin filament elongation by interacting with barbed ends, shielding them from capping protein. We conclude that Ena/VASP regulates cell motility by controlling the geometry of actin filament networks within lamellipodia.