Abstract: Integrins are adhesion receptors that connect cells to components of the extracellular matrix or to counter receptors on other cells. Besides mediating stable adhesion, these receptors are implicated in the deposition of extracellular matrices and they are crucial for cell migration. Integrin-mediated adhesion also modulates signal transduction cascades downstream of other receptors and thereby regulates cell survival, proliferation, and the expression of differentiation-related genes. In this review, an overview of the evidence for roles of integrins in tissue development and function is given and the contribution of changes in integrin expression to cancer is discussed.