1. The Walter and Eliza Hall Institute of Medical Research & Rotary Bone Marrow Research Laboratories (B.P., K.D.S., E.Y.M.S., M.O., S.W., G.J.L., J.E.V.), Post Office Royal Melbourne Hospital, Victoria 3050, Australia
2. Institute of Biomedical Sciences (T.K.T.), Academia Sinica, Taipei 115, Taiwan