The Molecular Mechanism of MAPK / ERK Inactivation

Extracellular signal-regulated kinases 1 and 2 (ERKs) are central regulators of many physiological and pathological processes. Their activity is regulated by phosphorylation on both tyrosine and threonine residues within their activation loops by MAPK / ERK kinases 1 and 2 (MEKs). Removal of phosphate from either the tyrosine, the threonine, or from both residues together can inactivate ERKs. Indeed members of the three groups of protein phosphatases, protein Ser / Thr phosphatase, protein Tyr phosphatase, and dual specificity phosphatases have been implicated in the inactivation of ERKs. In this review, we describe the various mechanisms involved in the inactivation of ERKs during different stages of mitogenic stimulation of quiescent cells.