1. AnorMED Inc., 200-20353 64th Avenue, Langley, British Columbia V2Y 1N5, Canada, Johnson Matthey Pharmaceutical Research, 1401 King Road, West Chester, Pennsylvania 19380, and Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium