1. Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA.
2. Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, CA 90095, USA.
3. Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
4. Department of Biological Chemistry, University of California, Los Angeles, CA 90095, USA.