FGF19 and hepatocellular carcinoma: The FGF19–FGFR4–KLB signal cascade was amplified via the activation of PI3K/AKT, RAS/RAF/MAPK, RAS/Ral/mTORC1, and GSK/β-catenin cell signaling pathways to further mediate the development and progression of HCC (Figure 2) (Wan et al., 2016).