FGFR4 and hepatocellular carcinoma: Numerous reports have suggested the central role of FGF19‐mediated signaling via FGFR4 in the pathogenesis of HCC.22, 24, 25, 26, 27, 28 FGF19‐/FGFR4‐mediated signaling is reported to strongly promote HCC proliferation; serum FGF19 is therefore believed to be an important candidate biomarker for treatment response to lenvatinib.