contributed equally to this study. contributed equally to this study. contributed equally to this study. ZHAO Wei-li,Shanghai Institute of Hematology, Shanghai Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China (Tel: 86-21-64377859. Fax: 86-21-64743206. Email: weili-zhao-sih@ yahoo.com) Dr. CHEN Sai-juan Shanghai Institute of Hematology, Shanghai Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China (Tel: 86-21-64377859. Fax: 86-21-64743206. Email: sjchen @stn.sh.cn; )