The protein encoded by FGFR1 gene is a member of the fibroblast growth factor receptor (FGFR) family, where amino acid sequence is highly conserved between members and throughout evolution. FGFR family members differ from one another in their ligand affinities and tissue distribution. A full-length representative protein consists of an extracellular region, composed of three immunoglobulin-like domains, a single hydrophobic membrane-spanning segment and a cytoplasmic tyrosine kinase domain. The extracellular portion of the protein interacts with fibroblast growth factors, setting in motion a cascade of downstream signals, ultimately influencing mitogenesis and differentiation. This particular family member binds both acidic and basic fibroblast growth factors and is involved in limb induction.Amplification or activation of FGFR1 has been reported in many cancers, including oral squamous cell carcinoma, breast cancer, esophageal squamous cell carcinoma, ovarian cancer, bladder cancer, prostate cancer, and lung cancer, predominantly in the squamous subtype. FGFR1 is altered in 2.86% of all cancers with breast invasive ductal carcinoma, lung adenocarcinoma, colon adenocarcinoma, invasive breast carcinoma, and breast invasive lobular carcinoma having the greatest prevalence of alterations.