The interaction of FGFs is achieved through a set of membrane-bound FGF receptors (FGFRs) expressed in multiple splice variants. FGFR1-4 have an intra cellular tyrosine kinase domain that is activated upon ligand binding leading to the activation of a number of downstream signals such RAF1, AKT1, signal transducer and activator of transcription (STATs) and MAPKs.