Characterization of HOXA-transduced cells. (A) Macroscopic aspect of methylcellulose cultures after 2 rounds of replating. HOXA13-transduced cells formed colonies surrounded by dispersed cells, whereas all other HOXA genes created colonies akin to the typical example of HOXA9transduced cells. (B) May-Grünwald-Giemsa–stained cytospin samples of cells explanted from a CFC assay of HOXA13 or HOXA13/ Meis1-transduced cells. Microphotographs of May-Grünwald-Giemsa–stained cells were taken at room temperature with a Nikon Digital Sight DS-Fi1 electronic camera attached to a Zeiss Axioskop with a Zeiss Neofluar 63×/1.25 objective and processed with Corel Draw software without any image enhancements. (C) FACS analysis of HOXA13-transduced cells explanted from methocel. (D) Morphology of cells obtained 6 days after inactivation of a conditional derivative of HOXA6 (HOXA6-ER). In the absence of the transforming HOX gene, cells stop proliferation and form mixed granulocytic/monocyte/macrophage cultures. Microphotograph was taken as described for panel B except that a 40× objective was used. (E) FACS staining of permanent cell lines derived from cells transduced with HOXA1, HOXA4, and HOXA6 either individually or in combination with Meis1 as indicated. As control similar lines derived from HOXA9 transduced cells are shown. Staining was performed with phycoerythrin-conjugated anti-Kit and fluorescein isothiocyanate-labeled anti-Gr-1 antibodies. (F) May-Grünwald-Giemsa–stained cytospins of the cells shown in panel A. Microphotographs of May-Grünwald-Giemsa–stained cells were taken at room temperature with a Nikon Digital Sight DS-Fi1 electronic camera attached to a Zeiss Axioskop with a Zeiss Neofluar 40×/1.25 objective and processed with Corel Draw software without any image enhancements.