1. Sino-American Collaborative Laboratory, State Key Laboratory of Experimental Haematology, Institute of Haematology and Blood Diseases Hospital, and Tissue Engineering Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300020, P.R. China.
2. Institute of Basic Medical Sciences and School of Basic Medicine, Center of Excellence in Tissue Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, P.R. China.
3. Department of Molecular Genetics, Microbiology and Immunology, University of Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical School, Piscataway, NJ 08854.