Focal adhesion kinase and tumour angiogenesis.

Angiogenesis, the formation of new blood vessels from pre-existing ones, is essential for tumour development. It is initiated and regulated by growth factors via their surface receptors, which activate several intracellular signalling pathways in endothelial cells. Cell adhesion molecules, such as integrins, also regulate angiogenesis. Despite these facts, inhibitors of endothelial cell growth factor receptors or integrins have not been as effective as initially hoped in the long-term inhibition of angiogenesis in cancer patients. Signalling downstream of growth factor receptors and integrins converge on the ubiquitously expressed non-receptor tyrosine kinase focal adhesion kinase (FAK). FAK is involved in endothelial cell proliferation, migration and survival, is up-regulated in many cancers and has recently been shown to control tumour angiogenesis. Indeed, FAK inhibitors are presently being developed for the treatment of cancer. However, recent studies have indicated the complexities of understanding the precise role for FAK in angiogenesis. Here we have summarized some of the key features of FAK, addressed some of the apparently contradictory roles of this molecule in angiogenesis and provided some perspectives for future studies.