Integrins are pivotal proteins in cell-cell adhesion, signaling and apoptosis. These properties render them attractive targets for drugs, especially those involved in cancer treatment. Recently, the structures of the extracellular domains of one of the integrin subtypes was solved with X-ray crystallography in the free form as well as bound to a ligand. These structures in combination with NMR spectroscopic data, electron microscopy images, and molecular modeling provide deeper insight into the mechanism of integrin-mediated signal transduction. The structures make structure-based rational drug design possible and are certainly hallmarks in integrin research.