Assaying PTEN catalysis in vitro.

PTEN is a major tumour suppressor protein and a regulator of numerous diverse biological processes. It has an evolutionarily conserved role as a phosphoinositide lipid phosphatase, regulating the PI3K signalling pathway, but also has catalytic phosphatase activity against protein substrates, although the significance of this latter activity is less well understood. Unlike many tumour suppressors, even modest changes in PTEN activity can have strong effects on phenotypes, including tumour formation. Due to this recognised functional significance, several experimental platforms have been developed to assay the catalytic activity of PTEN against different substrates and are being applied to understand this cellular substrate diversity and the regulation of PTEN. Here we present and discuss methods to assay the phosphatase activity of PTEN in vitro.