 Although PTP1B is generally studied as a regulator of metabolism, some research suggest it may have a role in tumor development, though whether it is oncogenic or tumor suppressive is unclear, as there is data in support of both arguments.The high ROS concentrations within cancer cells provide an environment for potential constitutive inactivation of PTP1B and it has been shown in two human cancer cell lines HepG2 and A431, that up to 40% of the Cys215 residues in PTP1B can be selectively irreversibly oxidized under these cellular conditions resulting in non-functional PTP1B.In addition, PTPN1 genetic ablation in p53 deficient mice resulted in an increased incidence of lymphomas and a decrease in overall survival rates.