Interestingly Msi2-reporter activity may mark stem cells in some other hematologic malignancies as well: in an MLL-AF9/NRASG12V-driven model of AML, all of the lethality associated with the disease was harbored within the GFP+ leukemia cells (Fig. 1j, k)24. The gene discussed is KMT2A; the disease is acute myeloid leukemia.