Immunohistochemical testing for Fascin aims to detect this actin-binding protein, which plays a role in cell motility and membrane protrusion. It is normally expressed in dendritic cells (such as Langerhans cells) and in some epithelial cells. It is used as an adjunct marker in the diagnosis of squamous cell carcinoma (particularly of the head, neck, and esophagus) and in the diagnosis of dendritic cell disorders such as Langerhans cell histiocytosis.