Affiliation: | (1) Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA, US;(2) Medizinische Hochschule Hannover, Institut für Molekularbiologie, D-30625 Hannover, Germany, DE;(3) European Molecular Biology Laboratory, Gene Expression Programme, P.O. Box 102209, D-69012 Heidelberg, Germany, DE |