CD38 and acute myeloid leukemia: Research studies following Lapidot et al. [5], however, have not disproved either the original theory of AML as composed by a hierarchically organized population of blasts with different abilities or the presence of L-IC mainly in the CD34+CD38− subpopulation: in fact, L-IC could be identified in the CD34+CD38− group in samples of all AML patients (versus <50% of patients in the case of CD34+CD38+) [4], and as few as 1000 CD34+CD38− L-IC managed to serially recapitulate the disease upon xenotransplantation [11].