It is a 54–58 kilodalton monomeric actin filament bundling protein originally isolated from sea urchin egg but also found in Drosophila[2] and vertebrates,[3] including humans.

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.

The role of Fascin in regulating cytoskeletal structures for the maintenance of cell adhesion, coordinating motility and invasion through interactions with signalling pathways is an active area of research especially from the cancer biology perspective.

In addition to CTLA-4 CD80/CD86 interaction fascin dependent polarization of cytoskeleton towards dendritic cell Treg immune synapse play a pivotal role.

In cancer, instead, TGF-β does not restrict NF-κB activity, and both can increase fascin expression, disrupting tissue structure and function.