PDCD1 and neoplasm: Moreover, ABCC4 ablation in tumors significantly enhanced PD-1 blockade efficacy and greatly improved survival of prostate cancer mice (Figure 7G), and also dramatically restored anti-tumor immunity of CD8+ T cells (Figure 7H and 7I), indicating that the ABCC4-PGE2 axis could be promising targets to overcome immune evasion and resistance to immunotherapy in prostate cancer (Figure 8).