This equilibrium status seems to be mainly promoted by adaptive immune cells and factors, such as CD4+/CD8+ T-cells, perforin-mediated toxicity by NK cells, IL-12 and IFN-γ, while cancer cells respond by increasing Treg and MDSC production of TGF-β, IL-10, ROS and NO and upregulating their own programmed death-ligand 1 (PD-L1) expression [229,231]. Here, TGFB1 is linked to cancer.