Fibroblast growth factor 19 is a protein that in humans is encoded by the FGF19 gene. The protein is a member of the fibroblast growth factor (FGF) family. FGF family members possess broad mitogenic and cell survival activities, and are involved in a variety of biological processes including embryonic development cell growth, morphogenesis, tissue repair, tumor growth and invasion. This growth factor is a high affinity, heparin dependent ligand for FGFR4. Expression of this gene was detected only in fetal but not adult brain tissue. It functions as a hormone, regulating bile acid synthesis, with effects on glucose and lipid metabolism. Reduced synthesis, and blood levels, may be a factor in chronic bile acid diarrhea and in certain metabolic disorders. FGF19 is frequently amplified in human cancers. Amplification of the FGF19 genomic locus was found in liver cancer, breast cancer, lung cancer, prostate cancer, bladder cancer, and esophageal cancer, among others. Targeting FGF19 inhibits tumor growth in colon cancer cells and hepatocellar carcinoma.