Cell-extracellular matrix and cell-cell interactions play critical roles during many physiological and pathological processes including morphogenesis and tumorigenesis. Many of the cellextracellular matrix and cell-cell interactions are mediated by cell adhesion molecules that are members of the integrin and cadherin families. Integrins are ␣␤ heterodimeric transmembrane glycoproteins that interact with extracellular (or other cell surface) molecules and cytoplasmic molecules, including cytoskeletal and catalytic signaling proteins (1-5). Recent studies indicate that integrins not only receive signals from extracellular matrix but also actively participate in the assembly of extracellular matrix (5-8).