1. Laboratory of Tumor Cell Biology, Developmental Therapeutics Program, National Cancer Institute, Bethesda, MD 20205.
2. Division of Hematology and Oncology, Washington University, St. Louis, MO 63110.
3. Clinical Oncology Program, National Cancer Institute, Bethesda, MD 20205.
4. Biotech Research Laboratories Inc., Rockville, MD 20850.