Fig. 5.

Model for the development of erythroleukemia in the absence of C/EBPα. Mouse studies support that bcr/abl transforms the hematopoietic stem cell (HSC) (6, 35). (Left) In the presence of C/EBPα, the majority of cells differentiate toward the granulocytic lineage, derived from the GMP. (Right) C/EBPα deficiency leads to a block from the CMP to the GMP stage and thus, the myeloproliferative effect of bcr/abl results in a predominance of early erythroid cells and mast cells. Our data show that C/EBPα retains its essential role for myeloid cell fate decision in malignant hematopoiesis. MEP, megakaryocyte/erythrocyte progenitor; McP, presumptive mast cell precursor.