1. Howard Hughes Medical Institute, Department of Molecular and Human Genetics, Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030
2. Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland 21218
3. Lawrence Berkeley National Laboratory, Life Sciences Division, Berkeley, California 94720
4. Aprogen. Joongwon-Gu, Sungnam-Shi, Kyunggi-Do, 462-807, Seoul, Korea, and
5. Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion 71110, Crete, Greece