Increased frequency of myeloblasts is a defining feature of AML, and the presence of this expanded CD34+ Mac1+ aberrant myeloid population in Mir142−/− animals strongly supported a role for Mir142 loss-of-function in promoting leukemogenesis; however, this population never rose above 10% of CD45+ cells in the bone marrow, consistent with the failure of Mir142 loss-of-function to promote leukemia in the absence of IDH2R140Q. Here, CD34 is linked to leukemia.