In the tumor microenvironment, PD-L1 and PD-L2 mRNA expression can be induced by immune cell-secreted inflammatory cytokines, such as Interferon-alpha (IFN-α), Interferon-beta (IFN-β), Interferon-gamma (IFN-γ), Interleukin 4, Interleukin 10, and granulocyte/macrophage colony-stimulating factor, resulting in adaptive immune resistance [15, 16, 20, 21]. This evidence concerns the gene PDCD1LG2 and neoplasm.