CD34-positive AML cases contain both leukemic CD34+ and CD34– cells, shown by the presence of molecular aberrancies in the CD34+ as well as the CD34– cell compartments (Figure 1B, AML-945), Within the CD34+ compartment, CD34+CD38– and CD34+CD38+ fractions contain mutated NPM1. Here, CD38 is linked to acute myeloid leukemia.