1. Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
2. Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, California Institute for Quantitative Biosciences, Center for RNA Systems Biology, University of California, San Francisco, San Francisco, CA 94158, USA.
3. The Mina and Everard Goodman Faculty of Life Sciences, The Bar-Ilan Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat Gan 5290002, Israel.
4. Department of Molecular and Cellular Biology, Harvard University, 52 Oxford St., Cambridge, MA 02138, USA.