FGFR4 and hepatocellular carcinoma: Fibroblast growth factor receptor 4 (FGFR4) is a promising target for the treatment of hepatocellular carcinoma, but current FGFR4 covalent inhibitors target only one of the two cysteine residues (Cys477 or Cys552) that provide FGFR4-specificity.