CD45+ EPCs from cancer patients and tumor-bearing mice can be induced to differentiate into myeloid cells 19; therefore, to determine whether these cells in mice with MPNs have myeloid differentiation potential, we purified CD45-Ter119+ cells from the spleens of MPN mice and cultured them in the presence of GM-CSF and mIL-6 in vitro 20. This evidence concerns the gene CSF2 and myeloproliferative disorder.