Characterization of the novel focal adhesion kinase RAFTK in hematopoietic cells

Protein tyrosine kinases (PTKs) mediate signals that respond to many pivotal cellular functions. Tyrosine phosphorylation, controlled by the coordinated actions of protein tyrosine phosphatases (PTPs) and PTKs, is a critical control mechanism for various physiological processes, including cell growth, differentiation, metabolism, cell cycle regulation and cytoskeleton function. The focal adhesion kinase (FAK) is a widely expressed non-receptor tyrosine kinase that is implicated in integrin-mediated signaling and plays a role in signal transduction pathways mediating cell adhesion, motility and anchorage-independent growth. Recently, we and others have identified a novel protein tyrosine kinase termed RAFTK, (also known as Pyk2 or Cak-beta), which is related to FAK. This review describes the role of RAFTK in various signaling cascades mainly in reference to hematopoietic cell lineages.