1. Medical Research Council Protein Phosphorylation Unit, Department of Biochemistry, University of Dundee, Dundee DD1 4HN, Scotland, U.K.,
2. Afdeling Biochemie, Faculteit der Geneeskunde, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
3. Department of Anatomy and Physiology, University of Dundee, Dundee DD1 4HN, Scotland, U.K.