1. Salivary Gland Disease Center and the Molecular Laboratory for Gene Therapy & Tooth Regeneration, Capital Medical University School of Stomatology, Tian Tan Xi Li No. 4, Beijing 100050, China;
2. Department of Cell Biology, Municipal Laboratory for Liver Protection and Regulation of Regeneration, Capital Medical University School of Basic Medical Sciences, You An Men Wai No.10, Beijing 100069, China;
3. The Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, 2250 Alcazar Street, CSA 103, Los Angeles, CA 90033, USA; and
4. Department of Biochemistry and Molecular Biology, Capital Medical University School of Basic Medical Sciences, You An Men Wai No.10, Beijing 100069, China