mTOR participates in the regulation of myeloid progenitor cell differentiation, while ERK1/2 controls the differentiation of APCs.119 Taken together, these data indicate that the effect of PD-1 blockade on TAMs should not be neglected, although it remains unclear whether patients with cancer with high PD-1+ TAM infiltration would also benefit from PD-1 blockade therapy. Here, PDCD1 is linked to cancer.