1. Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY 10032, USA.
2. Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University, 650 West 168th Street, New York, NY 10032, USA.
3. Howard Hughes Medical Institute, 650 West 168th Street, New York, NY 10032, USA.
4. Department of Biological Sciences, Columbia University, 650 West 168th Street, New York, NY 10032, USA.