To establish whether oncogenic CSF3R and CEBPA mutations collaborate in vivo to produce AML, we performed murine bone marrow transplantation with fetal liver hematopoietic cells harboring compound heterozygous CEBPA mutations (CEBPAK/L) or wild-type CEBPA retrovirally transduced with CSF3RT618I21. The gene discussed is CSF3R; the disease is acute myeloid leukemia.