Specifically, STAT3 is involved in “PD-L1 expression and PD-1 checkpoint pathway in cancer” (KEGG database) and “Cancer immunotherapy by PD-1 blockade” (WikiPathways), PTPN6 in “PD-L1 expression and PD-1 checkpoint pathway in cancer” (KEGG database)/“PD-1 signaling” (Reactome), and “Cancer immunotherapy by CTLA4 blockade” (WikiPathways), and PTPN11 is involved in all of the above. This evidence concerns the gene PDCD1 and cancer.