Adhesion molecules in cancer: the role of integrins.

It has been known for some time that cell adhesion receptors, including members of the integrin family, play an important role in the biology of tumors. Until recently, most of the emphasis in this area of research has concerned the functioning of integrins as adhesive molecules in the invasive and metastatic behavior of malignant cells. Now it has become clear that integrins can function as true receptors capable of transducing signals to the cell interior. Tyrosine phosphorylation seems to be a key aspect of integrin-mediated signal transduction, and a new tyrosine kinase has been described that seems to be important in this process. Evidence is accumulating that integrin-mediated signals can induce gene expression and affect transit through the cell cycle. Thus, the role of integrins in cancer seems not only to involve cell adhesion events, but may also involve the regulation of tumor cell growth and differentiation.