PDCD1 and neoplasm: In TILs, the CD8T, TEM in CD8T, NK and other subpopulations exhibited increasing expression percentage that correlated with the tumor progression changes, but the PD-1 and CTLA-4 expression intensity correlated negatively with the tumor growth stage (Figure 6A, * P < 0.05) in the Colon26 tumor animal model in both the tumor and the lymph node tissue (Figure 6B, * P < 0.05).