1. Department of Obstetrics, Gynecology and Reproductive Sciences, Center for Reproductive Sciences, University of California, San Francisco, San Francisco, CA 94143-0556.
2. Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Palo Alto, CA 94304-5542.
3. Department of Developmental Biology, Stanford University, Palo Alto, CA 94304-5329.
4. Department of Medicine (Oncology Division), Stanford University, Palo Alto, CA 94304–5329.