1. Laboratory of RNA Molecular Biology, The Rockefeller University, 1230 York Avenue, Box 186, New York, NY 10021, USA.
2. Biozentrum der Universität Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland.
3. Institut für Mikrobiologie und Hygiene, Abteilung Virologie, Haus 47, Universitätskliniken, D-66421 Homburg/Saar, Germany.
4. Columbia Genome Center, Columbia University, 1150 St. Nicholas Avenue, New York, NY 10032, USA.
5. Computational Biology Center, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.