Cd39 null CD4+ T cells inhibit tumor growth. (A) Tumor volumes of tumor-bearing Rag1−/− mice adoptively transferred with lymphocytes (CD4+ T cells, 1 × 106; CD8+ T cells, 0.5 × 106), followed by portal vein infusion of 2 × 105 luc-B16/F10 cells, on day 14. (B) Percent CD4+, CD8+, NK1.1+ and NKT lymphocytes of liver mononuclear cells isolated from tumor-bearing livers above. Data are given as means ± SEM. *P < .05, **P = .05.