Fli-1 gene deletion decreases the proliferation and enhances the differentiation of MEP-derived erythrocytic cells. Equivalent numbers of bone marrow MEP purified from injected Cre⁻ or Cre⁺ mice have been cultured for 5 days in liquid medium containing a complete cocktail of myeloid cytokines (IL3, IL11, TPO, EPO, SCF, GM-CSF, Flt3-l). (A) Histogram showing the decrease in the fold amplification of Cre⁺ MEPs (means and SDs from 7 different couples of Cre⁺ and Cre⁻ mice; P < .05). (B) Histogram showing the increased proportion of Ter119-positive cells in Cre⁺ MEP culture (means and SDs from the analyses of 5 different couples of Cre⁺ and Cre⁻ mice; P < .05). (C) Typical FACS diagram of cells after Ter119 and CD71 double-labeling. (D) Typical FACS diagram showing the increased proportion of small Ter119⁺ differentiated cells derived from Cre⁺ MEPs compared with Cre⁻ MEPs.