We recently found that ablation of the small GTPase Arf1 in tumor cells increased T‐cell infiltration and resulted in robust anti‐tumor effects in multiple mouse tumor models that are classically recalcitrant to immunotherapy.[27] In this study, we identified a mechanism that mediates the Arf1‐ablation‐induced anti‐tumor immunity. The gene discussed is ARF1; the disease is neoplasm.