The lymphoid-myeloid transdifferentiation potentials of members of the C/EBP 
family (C/EBPα, β, δ, and ε) were compared in v-Abl-immortalized primary B 
cells. Conversion of B cells to macrophages was readily induced by the ectopic 
expression of any C/EBP, and enhanced by endogenous C/EBPα and β activation. 
High transgene expression of C/EBPβ or C/EBPε, but not of C/EBPα or C/EBPδ, also 
induced the formation of granulocytes. Granulocytes and macrophages emerged in a 
mutually exclusive manner. C/EBPβ-expressing B cells produced 
granulocyte-macrophage progenitor (GMP)-like progenitors when subjected to 
selective pressure to eliminate lymphoid cells. The GMP-like progenitors 
remained self-renewing and cytokine-independent, and continuously produced 
macrophages and granulocytes. In addition to their suitability to study 
myelomonocytic lineage bifurcation, lineage-switched GMP-like progenitors could 
reflect the features of the lympho-myeloid lineage switch observed in leukemic 
progression.