1. Department of Organic Pharmaceutical Chemistry, Uppsala Biomedical Centre, Uppsala University, Box 574, SE-751 23 Uppsala, Sweden, Department of Biochemistry, Uppsala Biomedical Centre, Uppsala University, Box 576, SE-751 23 Uppsala, Sweden, Department of Cell and Molecular Biology, Uppsala Biomedical Centre, Uppsala University, Box 596, SE-751 24 Uppsala, Sweden, Medivir AB, Lunastigen 7, SE-141 44 Huddinge, Sweden, and Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106...