PDCD1 and neoplasm: Moreover, the proportions of Ki67+ CD8+ T cells and CD44hiCD62Llow CD8+ memory-like T cells in the spleen of tumor-irradiated PD-L1−/− mice were significantly higher than that in PD-L1 wt mice and non-irradiated PD-L1−/− mice (Figures 4G and 4H), and the expression of PD-1 in the intrasplenic CD8+ T cells of tumor-irradiated PD-L1−/− mice was increased after tumor IR (Figure 4I).