1. Institute of Basic Medical Sciences, Center for Tissue Engineering, Chinese Academy of Medical Science and Peking Union Medical College, Beijing; and Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Tianjin, People's Republic of China.
2. Department of Integrative Biology and Pharmacology, Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, Texas.