In addition to leukemic cells, HO-1 is reported to be overexpressed in CD34+CD38- as well as CD34+CD38- cells (both stem cells and progenitor cells) of AML patients compared to normal CD34+ cells, which brings to mind the idea of possible benefit of HO-1 silencing in eliminating the Minimal Residual Disease (MRD) [3]. The gene discussed is CD38; the disease is acute myeloid leukemia.