1. Department of Pathology, Yanbian University Medical College, Yanji City, Jilin Province, China
2. Oral Cancer Research Institute, College of Dentistry, Yonsei University, Seoul, Korea
3. Department of Oral and Maxillofacial Surgery, College of Dentistry, Yonsei University, Seoul, Korea
4. Dental Education Research Center, BK21 PLUS Project, College of Dentistry, Yonsei University, Seoul, Korea