Roles of protein tyrosine phosphatases in cell migration and adhesion

Signal transduction pathways are often seen as cascades of kinases, whereas phosphatases are relinquished to the housekeeping function of resetting th e individual elements to a resting state. However, critical biological proc esses such as cellular migration require a coordinated and constant remodel ing of the actin cytoskeleton as well as a rapid turnover of the cell-subst ratum linkages that necessitate the concomitant action of antagonistic enzy mes. Tyrosine phosphorylation was long known to be involved in adhesion and de-adhesion mediated via the integrin receptors. As the roles of tyrosine kinases such as focal adhesion kinase, c-Src, and Csk in this pathway are b eing extensively studied, increasing evidence is emerging about the importa nce of protein tyrosine phosphatases (PTP). In this review we discuss examp les of PTPs that were recently shown to play a role in cell adhesion and mi gration and their mechanism of action.