CD4 and hepatocellular carcinoma: SYVN1 knockdown/FoxO1 overexpression and anti-PD-L1 antibody exerted a similar effect on CD4+/CD8 + ratio and IFN-γ secretion, indicating that PD-L1 may play a critical role in SYVN1 knockdown- or FoxO1 overexpression-regulated immune evasion in HCC.