FACS strategy for isolation of AML cells based on expression of CD34, CD38, and CD71. (A) Cells labeled with anti-CD34-Cy5 (R2) were sorted on the basis of their expression of CD38-PE and CD71-FITC (B). Gate R1 cells were isolated as the CD34^- population. Sort gates in panels A and B were set to exclude 100% of the cells labeled with an isotype-control antibody.