In this study, we unexpectedly found that PARP1 inhibition by TLR9 (Figure 3B-C) led to a decrease in the PARylation and an increase in the Tyr705 phosphorylation of STAT3 to increase PD-L1 expression (Figure 3D, Figure 3I), which indicated that TLR9 regulated the crosstalk of STAT3 PARylation and phosphorylation by affecting PARP1 expression in HCC cells. This evidence concerns the gene CD274 and hepatocellular carcinoma.