Extracellular matrix: a matter of life and death.

Extracellular matrix (ECM) is an essential component of the stromal microenvironment both from a structural and a functional point of view. The ECM functions as a scaffold for tissue organization and regulates growth factors and chemokines availability thus contributing to maintain tissue homeostasis. Attachment of cells to ECM is essential to support cell survival, growth, and proliferation, and the lack of these interactions can trigger a type of cell death named anoikis. Several studies point out that alterations of ECM composition are often responsible of many pathological conditions such as cancer, of which it has been demonstrated to be occasionally the main promoter. ECM does not always represent a prosurvival stimulus; among the different array of ECM molecules a set of proteins can negatively affect cell viability and are thought to play an important role in tumor progression. For this reason attention has been focused on these molecules as potential tools or targets for therapy.