Importin beta-mediated nuclear import of fibroblast growth factor receptor: Role in cell proliferation

Although growth factor receptors are generally thought to carry out their r ole in signal transduction at the cell surface, many of these transmembrane proteins translocate to the nucleus after ligand stimulation. Here, we sho w that the nuclear translocation of fibroblast growth factor receptor (FGFR )1 occurs via a mechanism distinct from classical nuclear import but depend ent on importin beta, a component of multiple nuclear import pathways, Furt hermore, we show that nuclear FGFR1 induces c-Jun and is involved in the re gulation of cell proliferation. These data are the first description of a n uclear import pathway for transmembrane growth factor receptors and elucida te a novel signal transduction pathway from the cell surface to the nucleus .