PRF1 and neoplasm: ELISA analysis of tumor tissues revealed that B7 significantly enhanced IFN‐γ, TNF‐α, GzmB, and perforin levels (Figure 6J–M, P < 0.05 vs vehicle), whereas CD155 overexpression diminished this immunostimulatory functionality of B7 (Figure 6J–M, all P < 0.05 vs corresponding vehicle).