MTPAP and neoplasm: To further investigate the underlying mechanism of the potent anti-tumor efficacy of PLX-NP-P-aPD-1@Gel, the ongoing activation of P-aPD-1 was first visualized in the confocal images of tumors treated with WGA 594-labeled P-aPD-1 after surgery (Fig. 4a), as evidenced by the observation of the existence of PMPs in the tumor tissues.