A fibrous protein responsible for anchorage of actin filaments to the inner side of the cell membrane. Vinculin is located in patches called adhesion plaques on the cell membrane that are thought to be responsible for intercellular adhesion. Cells infected with Rous sarcoma virus (q.v.) produce a kinase that phosphorylates the tyrosine residues of vinculin. It is hypothesized that the phosphorylation of vinculin both destabilizes actin linkages (allowing transformed cells to become rounded) and weakens intercellular adhesion (allowing metastasis).