The many different kinds of blood cells found in the human body are derived from multi-potential stem cells, which are induced to differentiate into one or another cell type by the action of regulatory proteins or growth factors. This volume looks at the way that binding of these proteins to specific receptors causes changes in gene expression in the nucleus and the activity of certain enzymes in the cytoplasm, committing the cell to a particular developmental pathway. Also discussed are recently established clinical applications and clinical trials of new techniques.