Using a Qa-1b+ PD-L1+ A20 tumor model injected in BALB/c mice, in which both NK and CD8+ T cells are required to control tumor growth, almost half of the CD8+ tumor infiltrating lymphocytes (TILs) expressed PD-1 and importantly, half of them expressed NKG2A [27]. This evidence concerns the gene PDCD1 and neoplasm.