Analysis of protein phosphatases: toolbox for unraveling cell signaling networks.

Protein phosphatases reverse the covalent modifications of numerous cellular proteins imposed by the activation of protein kinases. Although protein phosphatases generally demonstrate broader substrate specificity than protein kinases, at least in vitro, these enzymes have evolved complex mechanisms to target specific physiological substrates and respond to physiological stimuli to control numerous physiological events. This chapter provides a brief overview of the challenges that faced researchers in protein phosphatases in years past and highlights numerous state-of-the-art techniques (described in greater detail in other chapters in this volume) available to today's scientists. These methods should equip investigators with a rich toolbox of reagents and techniques and promise a brighter future for the study of eukaryotic protein phosphatases. These experimental approaches should also facilitate future investigations directed at unraveling the role of phosphatases in signaling networks in human health and disease.