AbstractThe establishment of IL-3-dependent multipotent progenitor cell lines from Hox-2.4-expressing bone marrow cells suggests that homeobox genes may contribute to immortalization of early myeloid cells. A survey of 20 independently derived multipotent IL-3-dependent cell lines established from either src-virus-infected long-term bone marrow cultures (FDCP-mix) or Multi-CSF-virus (M3MuV)-infected bone marrow revealed that Hox-2.4 was not expressed in any of these cell lines. In addition DNA rearrangements were not observed. We conclude that activation of Hox-2.4 is not an obligatory event in the immortalization of early myeloid cells.