PDCD1 and neoplasm: In the absence of PD-1:PD-L1 blocking moieties, we observed that the green objective area of the eGFPPOS PD-L1POS tumor cells increased in time, signifying that tumor cells were not killed by activated T cells, and as such, confirming the inhibitory role of PD-L1 on tumor cell killing by PD-1POS CD8POS T cells (Figure 7C).