摘要: Fibroblast growth factors (FGFs) constitute a family of seven closely related polypeptide mitogens with profound biological activities.'They are relatively small (15–29 kDa) heparin binding proteins which are mitogenic for a wide variety of cell types from mesenchymal and neuroectodermal origin. Acidic FGF (aFGF) and basic FGF (bFGF), the two best characterized members of the FGF family, were the first to be cloned23 and have been shown to possess neurotrophic and angiogenic activities in addition to their mitogenic properties. Keratinocyte growth factor (KGF) may be a specific mitogen for cells of epithelial origin since it promotes growth of a limited spectrum of cell types. The other FGFs (FGF-5, 5 FGF-6, 6 int-2,'and hst/KFGF89) are expressed in specific temporal and spatial patterns in the developing embryo and in certain types of cancers." They are not generally found in adult tissues but they appear to have a spectrum of activities similar to aFGF and bFGF in vitro. 10-13The large number of FGF ligands and the diversity of their biological effects have prompted much effort toward isolation and characterization of FGF receptors. Three different tyrosine kinase linked FGF receptors have been identified (flg, bek, and CEK-2) and the presence of others has been indicated. ¹ Interestingly, all three gene products were initially isolated on the basis of their tyrosine kinase domains. A partial cDNA for human flg (fms-like gene) was first isolated by low stringency hybridization with a cDNA probe corresponding to the tyrosine kinase domain of the CSF-1 receptor." Flg was described as a bFGF receptor when the chicken protein was isolated by bFGF …