Conversely, it should be noted that some studies suggest that very high levels of NO, such as those produced by NO donors or potentially iNOS, may actually negatively regulate Th1 differentiation required for anti-tumor immunity by leading to the S-nitrosylation of key post-transcriptional regulators of Th1 cytokines and transcription factors (88–90). The gene discussed is NOS2; the disease is neoplasm.