Fascin (FSCN)

FSCN is a 54-58 kilodalton monomeric actin filament bundling protein originally isolated from sea urchin egg but also found in Drosophila and vertebrates, including humans. Fascin (from the Latin for bundle) is spaced at 11 nanometre intervals along the filament. The bundles in cross section are seen to be hexagonally packed, and the longitudinal spacing is compatible with a model where fascin cross-links at alternating 4 and 5 actins.

It does seem likely that it may be most closely related to the fimbrin/plastin group since it is, like them, calcium insensitive, monomeric and close in apparent molecular mass.Fascin binds beta-catenin, and colocalizes with it at the leading edges and borders of epithelial and endothelial cells. Fascin is a protein  encoded by the FSCN1 gene.