1. Y. Gu, G. Ku, K. Hsiao, M. A. Fleming, V. Sato, M. W. Harding, D. J. Livingston, M. S.-S. Su, Vertex Pharmaceuticals Inc., 130 Waverly Street, Cambridge, MA 02139, USA.
2. K. Kuida, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
3. H. Tsutsui, N. Hayashi, K. Higashino, H. Okamura, K. Nakanishi, Hyogo College of Medicine, 1-1, Mukogawa-cho, Nishinomiya, Japan.
4. M. Kurimoto and T. Tanimoto, Fujisaki Institute, Hayashibara Biochemical Laboratories, Hayashibara Company Inc., Okayama, Japan.
5. R. A. Flavell, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA.