(A) CD11b expression in parental and retrovirus-infected 32D cells. Cells were cultured in the presence of G-CSF for the indicated times, stained with fluoresceinated Mo1 monoclonal antibody, and analyzed by flow cytometry. Mean fluorescence intensity is shown in each panel; the bars represent the background staining of an isotype control antibody. (B) G-CSF receptor and c-myb expression during differentiation of 32D cells constitutively expressing PU.1 32D/PU.1 and 32D/LXSN cells were cultured in the presence of G-CSF. Total RNA was isolated at the indicated times, and 5 μg of each sample was electrophoresed, blotted, and hybridized to a c-myb cDNA probe. The filter was then stripped and hybridized to a G-CSF receptor cDNA and to a β-actin probe.