It has become clear that integrins have effects on tumorigenesis that are in addition to their role in mediating cell adhesion during invasive and metastatic processes. Integrins can transduce signals from the extracellular matrix to cell interior, via tyrosine kinases, and possibly by other mechanisms as well. These integrin mediated signals contribute to control of gene expression, to regulation of anchorage-dependence, to cell cycle transit, and to the control of tumor growth.