1. Molecular Genetics Laboratory, The Johns Hopkins Oncology Center, Baltimore, MD 21231.
2. The Oncology Center and Department of Pathology, The Johns Hopkins University and Hospital, Baltimore, MD 21205.
3. ICI Pharmaceuticals, Cheshire, United Kingdom.
4. Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84132.
5. Cancer Institute, Tokyo, Japan 170.