First, Turhan et al. did not observe PML-RARA expression in flow-sorted CD34+/CD38− cells (a cell population enriched for less mature hematopoietic progenitors, including stem cells), but did detect PML-RARA expression in CD34+/CD38+ cells (a population enriched for more mature hematopoietic progenitors, including early myeloid committed progenitors) from two APL patients, using semi-quantitative RT-PCR [7]. The gene discussed is CD38; the disease is acute promyelocytic leukemia.