Modulation of integrin affinity, valency and dynamics between the front and the rear of migrating cells. A) Schematic representation of integrin behavior in focal complexes versus focal contacts in migrating cells. Analysis of integrin dynamics in focal complexes revealed slow integrin exchange in Rac1 controlled anterior regions of the cell (vertical arrows). In focal contacts localized to the posterior domain of the cell, which is controlled by RhoA activity, integrin exchange rates are fast (circling arrows), resulting in focal contact plasticity and sliding. B) Cartoon of a migrating cell expressing low-and high-affinity integrins within its cell membrane. The differential integrin densities, integrin dynamics (circling arrow) and organization of the actin cytoskeleton between the front and the cell rear are represented. In addition, integrin transport is depicted by anterograde vesicular traffic and myosin-X driven transport along filopodia. C) Graphic representation of anterior to posterior modulations of relative integrin affinity, integrin valency and integrin dynamics in the plasma membrane. The greater the thickness of the bar, the more important is the specific type of integrin behavior. The combination of the three parameters define and predict the behavior of focal complexes or focal contacts in migrating cells.