PDCD1 and neoplasm: In addition, repeated stimulation of D1-receptor-expressing neurons in this region of tumor-bearing mice produced further decrease in the number of either TIM-3+ PD-1+ CD8+ T cells (Fig. 5b, Mann–Whitney test, *p < 0.05 vs D1-WT/hM3Dq) or LAG-3+ PD-1+ CD8+ T cells (Fig. 5e, Mann–Whitney test, **p < 0.01 vs D1-WT/hM3Dq) in the spleen.