PTPN1 and central nervous system cancer: In human glioma cells, it has been shown thattroglitazone activates protein-tyrosine phosphatase-1B (PTP-1B), whichsubsequently reduces phosphotyrosine 705 STAT3 (pY705-STAT3) via a PPARγ-independent pathway [53].Reduction of pY705-STAT3 in glioma cells caused downregulation of c-FLIP andBcl-2.