{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"PU.1 is a member of the Ets family of transcription factors and is required for the development of multiple hematopoietic lineages. It plays a pivotal role in normal myeloid differentiation and regulates the expression of immunoglobulin and other genes that are important for B-cell development. It is expressed in the myeloid lineage and in immature as well as mature B lymphocytes, with the exception of plasma cells. PU.1 is expressed in germinal center B-cells and mantle B-cells."}]}]}