The activity of CD8+ T cells was evaluated by measuring IFN‐γ release; IFN‐γ production in CD8+ T cells was significantly abated in CT26 cells than in 4T1 cells after ICAM‐1 depletion, suggesting that ICAM‐1 in CT26 cancer cells positively regulates CD8+ T cell activation (Figure 1e). Here, ICAM1 is linked to cancer.