Integrins: role in cell adhesion and communication.

Adhesive interactions are crucial for the integrity and function of all cells and tissues. As one of the major families of cell adhesion receptors, the integrins have been the focus of scientific interest for more than a decade. The resulting studies have tremendously enhanced the understanding of integrin-mediated adhesive interactions and have unveiled novel integrin functions in the cytoskeletal organization of microfilaments and in the activation of diverse signaling pathways. These functions are critically involved in the regulation of multiple processes, such as tissue development, inflammation, tumor cell growth and metastasis, and programmed cell death. The global view of integrin receptor biology has radically changed and has become much more subtle and elaborate. The enormous complexity of integrin function is determined by the heterodimeric formation of more than 20 functional integrin receptors, the cell type-specific distribution, the receptor activation state, the presence of different activation and deactivation signals, and the subsequent employment of distinct cytoskeletal and signaling complexes within a more dimensional network of time and space. This article summarizes the structural and functional properties of the integrin receptors and emphasizes some of the major achievements made in the past to enhance the understanding of integrin biology.