Protein phosphorylation is a reversible and dynamic post-translational modification that is governed by the opposing activities of protein phosphatases and kinases. Protein phosphatases remove phosphate groups covalently attached to serine, threonine, and tyrosine residues. By counteracting the activities of kinases, phosphatases play an important role in the control of a wide variety of cellular functions including cell cycle checkpoints, responsiveness to growth factors, contact inhibition, and cellular motility. Disturbances in phosphatase activity are implicated in a wide variety of disease states such as colon cancer, obesity, and immunodeficiencies. A number of successful drugs have been developed that target protein phosphatases.
