The effect of IM 5 μM and dasatinib 150 nM on recovery of undivided cells using CFSE high-resolution tracking of cell division. Primary CFSE⁺ CD34⁺ CML cells were cultured as described with assessment of recovery of undivided CFSE^max CD34⁺ cells by flow cytometry at 3 and 6 days. (A) Undivided CFSE^max cells (± SEM) remaining after 3 and (B) 6 days of culture. At 3 days, there was a significant accumulation of undivided CFSE^max cells in the IM and IM plus dasatinib arms in comparison to the no-drug control (P = .04 and P = .05, respectively), and after 6 days of culture, there was a significant accumulation of these cells in the IM-containing test arms in comparison to the non-IM–containing arms (P = .045). Das indicates dasatinib.