Vinculin couples as a focal adhesion protein the extracellular matrix (ECM) through integrins to the actomyosin cytoskeleton. During the last years vinculin has become the focus of cell mechanical measurements and a key protein regulating the transmission of contractile forces. In earlier reports vinculin has been described as an inhibitor of cell migration on planar substrates, because knock-out of vinculin in F9 mouse embryonic carcinoma cells and mouse embryonic fibroblasts showed increased cell motility on 2D substrates. The role of vinculin in cell invasion through a 3D extracellular matrix is still fragmentarily investigated. This review presents vinculin in its role as a regulator of cellular mechanical functions. Contractile force generation is reduced when vinculin is absent, or enhanced when vinculin is present. Moreover, the generation of contractile forces is a prerequisite for cell invasion through a dense 3D ECM, where the pore-size is smaller than the diameter of the cell nucleus (<2 microm). Measurements of cell's biophysical properties will be presented. In summary, vinculin's leading role among focal adhesion proteins in regulating the mechanical properties of cells will be discussed.