NUCLEAR-PROTEIN TYROSINE PHOSPHATASES AND CONTROL OF CELL-PROLIFERATION

Apart from playing a role in signal transduction pathways, tyrosine ph osphorylation has more recently been shown to regulate nuclear events such as cell division cycle and transcription factor activity. Members of the family of protein tyrosine kinases and protein tyrosine phosph atases (PTPases) that may be responsible for this regulation have been shown to localize in the nucleus. The nuclear PTPases are of particul ar interest because of their role in regulating cell proliferation. On e of them, PTP-S2 enhances cell proliferation and has the unique prope rty of binding to DNA. Many of the nuclear PTPases are induced by mito gens and may act as either positive or negative regulators of cell pro liferation, making them potential candidates for oncogenes and antionc ogenes (tumour-suppressor genes), respectively.