PRF1 and neoplasm: Murine models of lung AC have demonstrated that Tregs may inhibit CD8+ T cell-mediated anti-tumor immunity (Fig. 3b), with the depletion of Tregs resulting in tumor cell death and elevated levels of granzyme A, granzyme B, perforin and IFN-γ in infiltrating CD8+ T cells at early stages of tumorigenesis [66].