PYK2 and FAK in osteoclasts.

Integrin alpha(v)beta3 plays a pivotal role in osteoclastic bone resoprtion by mediating both osteoclast attachments on bone matrix and cytoskeleton reorganization. The focal adhesion kinase (FAK) family kinases including FAK and proline-rich tyrosine kinase 2 (PYK2) are major tyrosine kinases activated by integrin engagement. In osteoclasts, although FAK is expressed, PYK2 appears to be the predominant mediator of integrin alpha(v)beta3 signaling events that influence osteoclast physiology and pathology. Recent progress in the understanding of the role of PYK2/FAK kinases in the regulation of osteoclastic actin cytoskeletal organization, cell migration, and bone resorption will be discussed in this review.