Fascin, also known as 55 kDa actin-bundling protein, is an intracellular 55-58 kDa member of the fascin family of proteins. It has a restricted expression pattern, being found in oligodendrocytes, select endothelium, cerebellar stellate neurons, and blood. Fascin is found associated with actin in filopodia, and serves to coordinate and stabilize actin bundle formation, both in normal cells and tumor cells. Fascin expression is highly upregulated in many types of carcinomas including breast, colon, gastric, and oral squamous cell carcinomas. In these cancers, increased Fascin expression is linked to increased aggressiveness and high mortality. Thus, Fascin is a common biomarker for aggressive carcinomas, can be used as a histological marker of particular cancer subtypes, and may be a useful therapeutic target.