P-CrKL in CD34⁺CD38^– CML cells treated with 5 μM IM, 10 nM, and 150 nM dasatinib. As described in Figure 3, CD34⁺CD38^– CML cells were cultured with or without IM (5 μM), 10 or 150 nM dasatinib. CD34⁺CD38^– CML cells treated with IM showed no significant inhibition of CrKL phosphorylation at either 16 or 72 hours. Dasatinib (10 nM)–treated CD34⁺CD38^– CML cells showed a 26% reduction in P-CrKL at 16 hours, as compared to no-drug control (100%), which was not significantly different to IM-treated cells (P = .30). After 72 hours, the difference between IM and dasatinib 10 nM was significant (P = .001). CD34⁺CD38^– CML cells treated with 150 nM dasatinib showed increasing inhibition of CrKL phosphorylation at 16 and 72 hours (–66% and –79% of control, respectively) (P = .007 and .005 versus dasatinib 10 nM and P = .004 and P < .001 versus IM 5 μM). Das indicates dasatinib.