Moreover, the HGF/c-MET and FGF19/FGFR4 axes synergize via the ERK1/2-ETV4 axis to upregulate PD-L1 and CCL2 expression in TAMs and MDSCs, suppressing CD8+ T-cell activity and driving HCC metastasis (70). This evidence concerns the gene FGFR4 and hepatocellular carcinoma.