What’s more, PTPN2 deficiency in T cells boosts the generation of Tim-3+ cells, CD44+ effector/memory T cells, and CD8+ T cell infiltration and cytotoxicity in tumors, as well as the efficacy of anti- programmed cell death protein 1 (PD-1) and CAR T cells in solid tumors by promoting activation of Src family kinase LCK and cytokine-induced STAT-5 signaling (195, 197–199), which can actually facilitate tumor control and improve immunotherapy potency. This evidence concerns the gene PDCD1 and neoplasm.