Effects of retroviral expression of PU.1 on megakaryocytic differentiation in the presence of GATA-2. (A) Schematic diagram of the experiment. On day 5, cells were infected with control EYFP or PU.1-IRES-EYFP retrovirus, and expression of GATA-2 was induced. EYFP⁺ cells were sorted and examined on day 9. (B) May-Giemsa staining of the cells. Infected retroviruses and the expression of GATA-2 are as indicated. (C) Surface expression patterns of Mac-1, GPV, and TER-119. (D) Expression of CD71 in PU.1-IRES-EYFP-infected cells at day 9. Monoclonal antibodies used for staining are indicated (C-D).