Wild-type v-Myb and ΔP1 v-Myb progenitors develop into different lineages.

(A) Flow cytometry of progenitor cells grown in the presence of TGFα, bFGF, and SCF (+GF) and induced to differentiate by removal of growth factors and TPA treatment (+TPA). Monoclonal antibodies specific for the erythroid JS4 antigen (red) or myeloid antigens MC51/2, MC47/83, and MC22/3 (shades of blue) were used. Negative controls are represented by empty curves. Plots axes are as in Figure 2D. (B) Cytochemical staining and immunofluorescence of progenitors induced to differentiate by growth factor withdrawal (-GF) and TPA treatment (+TPA). Left panels: myeloperoxidase staining for identification of eosinophilic granules. Middle panels: Giemsa staining to reveal cell morphology; Astra blue staining of heterophilic granules (inset in ΔP1 panel). Right panels: indirect immunofluorescence with 11C3 monoclonal antibody to reveal thrombocytes (green). Inset in ΔP1 panel, double-staining with 11C3 (green) and anti-GATA-1 (red) antibodies. The bar represents 15 μm.