(A) Isotype control antibodies (IgG) or anti-CD8 (2.43) antibody were administered i.p. to PIM-2^–/– tumor-bearing mice twice weekly (200 μg/mouse). Depletion of CD8⁺ T cells was confirmed by flow cytometry before tumor infusion. (B) Survival of tumor-bearing mice treated with antibody was monitored until day 70. WT tumor-bearing mice given IgG and heterozygous PIM-2 mice (PIM-2^+/–) with no treatment were used as control groups (n = 6 mice per group). (C) Diagram of adoptive T cell transfer. 2 × 10⁵ TS-1 tumor cells were infused into mice, and tumors were allowed to establish in WT mice for 6 days. Tumor-bearing mice were sublethally irradiated at 500 cGy followed by transfer of 2 × 10⁶ CD8⁺ T cells isolated from WT and PIM-2^–/– mice. Irradiated tumor-bearing mice without T cell transfer were used as controls. (D) Survival of tumor-bearing mice is shown until day 100 (n = 9 mice per group). (E–G) B6 mice were injected i.v. with 5 × 10⁵ B16 tumor cells and tumors that were allowed to establish for 6 days. These tumor-bearing mice were sublethally irradiated and received adoptive transfer of 1 × 10⁶ Pmel-1 cells in which PIM-2 was silenced with LV-shPIM-2. (E) Virus transduction efficiency is illustrated by percentages of GFP⁺ cells. Transduced Pmel-1 cells were stimulated with PMA and ionomycin and measured for IFN-γ and TNF-α secretion. (F) Tumor growth was monitored with bioluminescent imaging. (G) Survival of tumor-bearing mice is depicted (n = 9–10 mice per group) by log-rank test. *P < 0.05, ***P < 0.001.