Phosphatases and tumorigenesis.

Phosphatases are regulatory enzymes that antagonize the action of kinases within the cell. An understanding of the contribution of kinases to cancer has emerged during the past two decades; however, our understanding of phosphatases in cancer has lagged behind. Currently, three phosphatases have been implicated in the etiology of tumors: protein phosphatase 2A, CDC25A/B, and PTEN (or MMAC1). Protein phosphatase 2A and PTEN behave as tumor suppressors, whereas CDC25A and -B act as oncogenes.