CTLA4 and colonic neoplasm: To test this hypothesis, we employed CT26, a murine colon cancer model with high CD8+ T cell infiltration [47], using mock- or ULBP2-transfected tumor cells to examine the impact of ectopic ULBP2 expression under T cell-modulatory conditions with anti-CD4, anti-CD25, and anti-CTLA-4 antibody treatments.