CMTM4 and hepatocellular carcinoma: In this study, though we failed to find the significance of single CMTM4, PD-L1, CD4 or CD8 expression in the prognosis of HCC patients due to small HCC sample size for IHC detection, the high co-expression of CMTM4 and PD-L1 combining with high CD4 expression showed a better HCC prognosis, further supporting that CMTM4 as a regulatory factor in HCC TME could control the immune effect of PD-L1.