Protein tyrosine phosphatases as drug targets: PTP1B and beyond

Protein tyrosine phosphatases (PTPs) control signal transduction pathways and have recently emerged as potential drug targets. Inhibition of individual PTPs can result in the activation of therapeutically relevant kinase cascades. This is particularly useful in cases where disease is associated with hormonal resistance, such as insensitivity to insulin or leptin. Currently, PTP1B is being investigated by a number of companies as a promising target for leptin/insulin mimetics and in the treatment of diabetes and obesity. Since all 90-100 PTPs have been identified in the human genome, the challenge now is to identify the function of these enzymes and the therapeutic indications that may exist for specific PTP inhibitors.