Upon further investigation, cancer-related signaling pathways, P53 hypoxia, TNF receptor-associated factor 6–mediated (TRAF6-mediated), IFN regulatory factor 7 (IRF-7) activation, NKT pathway and inhibitory immune checkpoint receptors, T cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT), PD-1, and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) were found to be upregulated in mice splenic Tregs [106]. This evidence concerns the gene PDCD1 and cancer.