CD274 and cancer: While previous studies have suggested the inhibitory contribution of PD-L1 expressed on cancer cells (16, 18, 63), in our system, the proportion of PD-L1+ HepG2-preS1-GFP cells did not change significantly with the presence of HBV-specific TCR T cells and/or monocytes, and these proportions were much lower than those observed for monocytes.