Cell signalling in vascular cells exposed to cyclic strain: the emerging role of protein phosphatases

Phosphorylation of tyrosine or serine/threonine residues of intracellular proteins is a reversible and dynamic process which is essential in controlling cellular growth, migration and survival. The phosphorylation states of numerous intermediary signalling proteins are governed by the opposing activities of protein kinases and phosphatases. Abnormal phosphorylation states have been linked with many human diseases, including cancer, diabetes, hypertension and cardiac hypertrophy. Recently, several reports have described the role of phosphatases in regulating critical cellular functions and signalling pathways in vascular cells. This Review will focus on the significance of several of these phosphatases and present information on the role of protein phosphatase type 2a in endothelial cells exposed to haemodynamic forces.