FGFR1 (Fibroblast growth factor receptor 1), also known as basic fibroblast growth factor receptor 1 (BFGF-R-1), heparin-binding growth factor receptor (HBGFR), FMS-like tyrosine kinase 2 (FLT2), CEK, FLG, HH2 or OGD, is an approximately 91 kDa cell surface receptor that consists of an extracellular ligand-binding domain, an intracellular catalytic domain and a transmembrane domain. It belongs to the fibroblast growth factor receptor (FGFR) family and is a receptor tyrosine kinase composed of 822 amino acids and encoded on the chromosome 8p11.23. FGFR1 has intracellular tyrosine kinase activity and plays a key role in the regulation of cell proliferation, differentiation, and migration, as well as in embryonic development. There are many splicing forms of this gene and its mutations have been involved in diseases including Antley-Bixler syndrome, Jackson-Weiss syndrome, Pfeiffer syndrome, and autosomal dominant Kallmann syndrome 2. KLB (Klotho beta), also known as Beta-klotho (BKL), B-klotho, BetaKlotho or klotho beta like 3, has a big molecular weight of about 119.8 kDa and encoded by the gene located at the chromosome 4p14. It is a 1,043-amino acid protein, whose related pathways involve RET signaling and cytokine signaling in the immune system. KLB is reported to be a key receptor component for the endocrine fibroblast growth factors (FGFs), FGF19 and FGF21. And it is believed to contribute to the transcriptional repression of cholesterol 7-alpha-hydroxylase, a rate-limiting enzyme in the bile acid synthesis. In the mouse, full-length Klb has been found and cloned, sharing 41.2% identity with mouse Kl. They all contain an N-terminal signal sequence, two tandemly repeated glycosidase-like domains, a C-terminal transmembrane domain, and a short cytoplasmic tail.