In the 1990s, a detailed investigation of AML subpopulations provided the first proof of a rare LSC population, with a CD34+/CD38- phenotype, within AML capable of establishing leukemia in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice: leukemic stem cells (LSCs)[11,12]. The gene discussed is CD38; the disease is leukemia.