Institution: | (1) Central Research Units, F. Hoffmann-La Roche & Co. Ltd., CH-4002 Basel, Switzerland;(2) Th. Kocher Institut, CH-3012 Bern, Switzerland;(3) Biochemical Institute, University of Zurich, CH-8093 Zurich, Switzerland;(4) Present address: Center for Cell Biology, University of Bern, CH-3012 Bern, Switzerland |