pH60/Surv vaccine induces long-term protection against tumor cell challenge. Mice were challenged by intravenous injection of 1 × 10⁵ CT-26 colon carcinoma cells 5 months after the second vaccination and were killed 20 days later. (A) Average lung weight of challenged mice. Average lung weight of healthy mice was approximately 0.2 g. ^*P < .02 compared with pBud control group. (B) Splenocytes were stimulated in vitro for 5 days with irradiated CT-26 cells and then used in a standard ⁵¹Cr-release assay against CT-26 target cells. ^*P < .01 compared with pBud control group.