UNC Blood Research Center, Division of Hematology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, USA

Correspondence to Nigel Mackman, PhD, Division of Hematology, Department of Medicine, University of North Carolina at Chapel Hill, 116 Manning Drive, Mary Ellen Jones Building, Room 8004B, Campus Box 7035, Chapel Hill, NC 27599, USA. Tel: +1 919 843 9543; fax: +1 919 843 4896; e-mail: [email protected]