1. Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037
2. The Harold L. Dorris Neurological Research Center, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
3. Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
4. The Institute of Childhood and Neglected Diseases, The Scripps Research Institute, La Jolla, California 92037