Table 2.

Comparison of villin and fascin and their role in filopodia assembly and turnover in normal and transformed epithelial cells

Characteristics	Villin	Fascin
Expression	Expressed in epithelial cells of the gastrointestinal tract; urogenital tract; exocrine glands of endodermic lineage, brush cells, merkel cells, osteocytes, taste receptor cells. Expressed in all carcinomas and intestinal metaplasia.	Expressed in neuronal, glial, endothelial and dendritic cells. Not expressed in epithelial cells. Expressed in some transformed epithelial cell lines and some carcinomas such as squamous cell carcinomas.
Expression in transformed epithelial cell lines	Expression increases as cells become polarized and differentiated.	Expression decreases as cells become polarized and differentiated.
Localization	Associated with microvilli and terminal web in polarized epithelial cell lines.	Associated with cell-cell contacts in transformed epithelial cell lines.
Metastasis	Associated with EMT.	Not associated with EMT.
Filopodia location	Assembles filopodia at leading edge.	Assembles filopodia at leading edge of mesenchymal cells and in carcinomas may assemble filopodia at cell-cell contacts.
Filopodia dynamics	May regulate dynamics and turnover of filopodia.	May assemble rigid filaments in filopodia and regulate stability of filopodia.
Actin Dynamics	Can nucleate, cap, sever and bundle actin filaments.	Can bundle actin filaments.
Capping activity	Could cap filaments to regulate filopodia assembly and turnover.	Has no actin capping function.
Nucleation activity	Could nucleate actin assembly in filopodia.	Has no actin nucleating function.
PtdIns(4,5)P2	Binds PtdIns(4,5)P2 and could generate evaginations or stabilize protrusions of filopodia by PtdIns(4,5)P2 clustering.	Does not bind PtdIns(4,5)P2.