Phenotype of clones obtained after step 2. The “immortal” clone B has the lowest frequency of differentiating myeloid cells. (A) Cytospin preparations of mock-expanded cells and one “immortal” clone selected after transduction with LTRSFeGFP (May-Grünwald/Giemsa staining). In no case did we detect mature forms of the granulocytic lineage. Images were visualized using an Olympus BX51 upright microscope (Olympus, Hamburg, Germany) equipped with a 40 ×/0.75 numeric aperture objective lens. Images were processed using the Colorview Soft Imaging System and analySIS Five software (Olympus). (B) Clones were subjected to FACS analysis using antibodies as indicated.