1. Departments of Developmental Biology (Q.Y., D.S., T.S., M.D., B.L.), Harvard School of Dental Medicine, Boston, Massachusetts 02115
2. State Key Laboratory of Oral Diseases (Q.Y.), Sichuan University, Chengdu 610041, People's Republic of China
3. Oral Medicine, Infection, and Immunity (H.S.), Harvard School of Dental Medicine, Boston, Massachusetts 02115
4. Department of Biomedical Sciences (C.S., R.G.E.), Institute of Physiology, Pathophysiology, and Biophysics, University of Veterinary Medicine, Vienna 1210, Austria