P21-activated kinases in human cancer

A balance between proliferation, differentiation, migration and death of cells is critical for the normal development of an organism. Perturbations of this balance can contribute to cancer development. The p21-activated serine/threonine kinases (Paks) play an important role in a variety of cellular functions including cell morphogenesis, motility, survival, angiogenesis, and mitosis. Paks were initially identified as an effector molecules of RHO GTPases; however, recent evidence that they can be activated in both GTPase-dependent and -independent manners expands our understanding of their physiologic functions. Paks play an important role in growth factor signaling, leading to cytoskeletal reorganization that subsequently influences growth factor-mediated cell migration and metastasis functions. Recent findings that Paks play a role in mitosis, nuclear receptor-signaling and deregulation of Pak in cancer cells suggest that these kinases play an important role in both normal development and cancer progression. In this review, we summarize the results of recent advances into the role of Paks in tumorigenesis and metastasis.