Affiliation: | (1) Molecular Hematology Laboratory, Department of Internal Medicine (Cancer Research), West-German Cancer Center, University of Essen, Hufelandstrasse 55, D-4300 Essen 1, Federal Republic of Germany;(2) Present address: Center for Cancer Research, Massachusetts Institute of Technology, E 17-517, 40 Ames Street, 02139 Cambridge, MA, USA |