INTEGRIN-mediated interactions between cells and extracellular matrix proteins influence a variety of biological processes, such as cell growth, differentiation and migration. The aim of our work is to elucidate molecular mechanisms of integrin-mediated SIGNALING that are involved in normal growth regulation, and, if inadvertently activated, may contribute to the phenotype of malignant cells. Our main focus is on tyrosine kinases and tyrosine PHOSPHORYLATION events initiated in FOCAL ADHESIONS, which are sites of close cell-matrix contacts, and in which integrins cluster following ligand binding. An understanding of the integrin signaling mechanisms may lead to ways of preventing malignant TRANSFORMATION.