Fig. 7. Model of vinculin involvement in the regulation of adhesion turnover. In motile cells, areas with both high adhesion turnover and high actin dynamics under the control of the small GTPase Rac depend on elevated PIP₂ levels, which leads to a weakening of the interaction of vinculin-containing adhesions with actin filaments. When acidic phospholipid binding to vinculin is defective, adhesion sites are stabilized and efficient progression of lamellipodia is impaired. This leads to a delay in cell spreading and an almost complete inhibition of cell motility in vinculin-LD-expressing cells.