Radio-iodinated FGF19 exhibited an affinity with a Kd value of 303 pM to the FGFR1-KLB complex expressed on the T-Rex 293 cells [4] (Fig. 2A), and 778 pM to a hepatocellular carcinoma cells expressing FGFR4 and KLB [4], [8] (Fig. 2B). Here, FGFR4 is linked to hepatocellular carcinoma.