This volume of Molecular Biology of Hematopoiesis is dedicated to John W. Adam­ son, M. D. , Tadamitsu Kishimoto, M. D. , Robert C. Gallo, M. D. , Arthur W. Nienhuis, M. D. , and Franco Mandelli, M. D. , for their contributions in developing an overall view of the state-of-the-art knowledge in the field of hematopoiesis. Richard Champlin, among other renowned clinicians, presented updated information on stem cells and T-cell depletion for bone marrow transplant. A clinical update on thrombopoietin was presented by Pamela Hunt of Amgen and by Kenneth Kaushansky. Arthur Nienhuis' and Katherine Turner's contributions to our current knowledge and advances in the fields of growth factors and gene transfer were also recognized during the 9th Symposium on Molecular Biology of Hematopoiesis in Genoa. The chapters cover such diverse areas as preclinical and clinical updates on growth factors and positive and negative regulatory molecules. "Advances in Leukemia: Mechanism and Treatment by Interferon" was presented by Professor Sante Tura. Readers will find presentation of exciting advances that have occurred in the area of hematopoiesis. The elucidation of gene structures of key growth factor proteins such as IL-12 and IL-II will lead to new insights and new approaches in understanding the regulation of hematopoiesis, as well as application of new growth factors.