FGF19 (fibroblast growth factor 19) is an endocrine growth factor that regulates bile acid homeostasis and metabolism through FGFR4 signaling. Primary functions include suppression of bile acid biosynthesis via negative feedback mechanisms involving the ileal farnesoid X receptor and hepatic KLB/FGFR4 complexes 1. FGF19 also regulates glucose, lipid, and energy metabolism through interactions with KLB and FGFR1-3 receptor complexes 1. Mechanistically, FGF19 activates ERK1/2 and JAK2-STAT3 signaling pathways to exert its effects 23. In disease contexts, FGF19 demonstrates significant oncogenic potential, promoting hepatocellular carcinoma and colorectal cancer metastasis through multiple mechanisms including ETV4 upregulation, PD-L1 expression, and creation of immunosuppressive tumor microenvironments 42. FGF19 facilitates cancer-associated fibroblast activation and neutrophil extracellular trap formation, enhancing metastatic potential 25. Clinically, FGF19-based therapeutics show promise for treating cholestatic diseases like primary biliary cholangitis and metabolic disorders such as NASH, while FGFR4 inhibitors represent potential cancer treatments 1. However, chr11 FGF19 administration raises oncogenic concerns due to its mitogenic effects 1.