PDCD1 and cancer: To further verify the significance of Rab37-mediated PD-1 PM presentation in PBMCs from nine lung cancer patients, we cultured human PBMCs for 7 days and then analyzed Rab37 mRNA expression, PD-1+/TIM3+/CD8+ expression, GzmB+/IFN-γ+/CD8+ expression and cancer cell viability of the PBMCs (Fig. 4G).