Fibroblast growth factor receptor 3 (FGFR3), also known as CD333, is a tyrosine kinase receptor located on the cell membrane and belongs to the FGFR family. The FGFR3 gene is located on human chromosome 4 at p16.3 and contains 19 exons, expressing several slightly different isoforms. FGFR3 protein structure comprises an extracellular structure with 2 or 3 immunoglobulin-like domains, a transmembrane domain and a cytoplasmic tyrosine kinase domain. When the extracellular portion binds with FGF, FGFR3 dimerizes and autophosphorylates and then triggers a downstream signaling cascade that ultimately affects cell growth, migration, angiogenesis, and differentiation.