1. K. Fukasawa, T. Choi, S. Rulong, G. F. Vande Woude, ABL-Basic Research Program, National Cancer Institute, Frederick Cancer Research and Development Center, Post Office Box B, Frederick, MD 21702-1201, USA.
2. R. Kuriyama, Department of Cell Biology and Neuroanatomy, University of Minnesota Medical School, Minneapolis, MN 55455, USA.