1. Laboratory of Molecular Signaling and Apoptosis, Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, 1011 N. University Ave., Ann Arbor, MI 48109-1078, USA;
2. School of Stomatology, Peking University Health Science Center, Beijing, China;
3. Division of Operative Dentistry and Endodontics, Department of Oral Medicine, Kanagawa Dental College, Kanagawa, Japan; and
4. Section of Oral Biology, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA;