1. AstraZeneca, Mereside, Alderley Park, Macclesfield, Cheshire SK10 4TG, England, AstraZeneca, Centre de recherches, Z. I. La Pompelle, BP 401, 51064 Reims, France, and Drug Development Section, Institute of Cancer Research, 15 Cotswold Road, Sutton, Surrey SM2 5NG, England