Jun expression in BM drives differentiation along the monocytic lineage. B6 BM cells were enriched for Lin^neg progenitors and infected with Jun/Venus or Venus vectors and sorted for Venus expression before plating into methylcellulose cultures stimulated with a cytokine cocktail. (A) Flow cytometric analysis of cells isolated from methylcellulose cultures after 1 week show the loss of Gr1⁺ cells in cultures infected with Jun. Percentage of cells within each immunotyped population is indicated. Typical results of 2 independent experiments. (B) Cytospins of cells isolated from methylcellulose cultures from Jun- or Venus-retroviral vector–infected B6 BM cells demonstrate the absence of granulocytic forms in Jun cultures, consistent with the results from the FACS analysis.