Actin-binding protein that contains 2 major actin binding sites (By similarity). Organizes filamentous actin into parallel bundles (PubMed:7738015). Plays a role in the organization of actin filament bundles and the formation of microspikes, membrane ruffles, and stress fibers (By similarity). Important for the formation of a diverse set of cell protrusions, such as filopodia, and for cell motility and migration (PubMed:21685497). Mediates reorganization of the actin cytoskeleton and axon growth cone collapse in response to NGF (By similarity). Interacts with RUFY3 (via N-terminus); the interaction induces neuron axon development (PubMed:24720729). Interacts with NGFR (By similarity). Associates with CTNNB1 (PubMed:8794867). Interacts with PLXNB3 (PubMed:21706053). Colocalized with RUFY3 and F-actin at filipodia of the axonal growth cone (PubMed:24720729). Colocalized with DBN1 and F-actin at the transitional domain of the axonal growth cone (PubMed:24720729). Most abundant in brain. Detected at lower levels in lung, uterus, small intestine and spleen (at protein level). Composed of four fascin beta-trefoil domains. Phosphorylation at Ser-39 inhibits actin-binding. Phosphorylation is required for the reorganization of the actin cytoskeleton in response to NGF. Belongs to the fascin family.