Negative staining EM images of fascin-induced actin filaments exposed to cofilin. Preformed 1 μM F-actin filament bundles, 10× diluted in a F-buffer solution containing 200 nM fascin, (top) with or (bottom) without 500 nM cofilin, were deposited on an EM grid and negatively stained. Bundles display clear cuts in the presence of cofilin (black arrows) with filament ends extending over 60 nm (±42 nm, SD, n = 37 breaks analyzed). Scale bars are 200 nm.