AbstractCell adhesion and migration are essential for embryonic development, tissue regeneration, and immune defence. The physical link between the extracellular substrate and the actin cytoskeleton is mediated by receptors of the integrin family and a large set of adaptor proteins. During cell migration this physical link is dynamically modified, allowing the cell to sense and adapt to the microenvironment. This includes the formation of integrin clusters at the cell front, their stabilization in the cell body and subsequent disassembly of these clusters at the rear of the cell. The modulation of the adhesion strength of the cell to the substrate is regulated by the affinity switch of integrin molecules and increased avidity through clustering of integrins. Here we explain how integrins mediate cell migration and how genetic defects of integrins and their adaptors lead to cellular dysfunction and generate pathological situations. Copyright © 2003 John Wiley & Sons, Ltd.