STAT1 and neoplasm: One pathway that was found to be significantly upregulated in the tumor of both PD-1Ab-treated and PD-1cKO mice was the IFNγ signaling pathway and its associated downstream molecules such as stat-1 and tbx21. In this respect, downregulation of specifically Ptpn2 was shown to correlate with tumor growth inhibition through enhancement IFNγ signaling by phosphorylation of STAT1, indicating a specific role for ptpn2 in regulating IFNγ signaling and effective tumor immunity (10).