1. Department of Anatomy and Cell Biology, Institute of Cancer Research and Translational Medicine, Medical Research Center, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland
2. Department of Prosthetic Dentistry and Stomatognathic Physiology, Institute of Dentistry, University of Turku, 20520 Turku, Finland
3. Department of Chemistry, University of Helsinki, P.O. Box 55, 00014 Helsinki, Finland