Curvature of cofilin-actin segments induced by the flow may accelerate severing. (A) Schematics illustrating how a microfluidics flow may accelerate severing at the barbed end side of a cofilin-decorated segment. Once a cofilin cluster has severed at its pointed end side, the flow may induce a high curvature at its barbed end side, which results in an increase of the severing at this boundary (Wioland et al., 2019b). (B) Microfluidics assay where single filaments and two-filament bundles are exposed to fascin and cofilin in the absence of actin. Severing at the pointed end side of cofilin clusters creates free barbed ends which depolymerize. Representative kymographs are shown (scale bar = 5 µm). Red arrows indicate pointed end side severing events which are accompanied with the departure of the cofilin cluster (i.e., due to accelerated severing at the barbed end side, as depicted in A), and black arrows severing events where it is not. 46% of the severing events leads to accelerated cofilin-segment departure (n = 26 events).