Inhibition of PAK kinase activity reduced ROS in LSCs. Lin⁻CD34⁺ cells from healthy donors and CML-CP patients were untreated (black and gray bars, respectively) or treated (white bars) with (A-B) 1 μM imatinib and (C-D) 1 μM imatinib (IM), 90nM dasatinib (DAS), 2 μM nilotinib (NIL), 30 μM IPA3, and a combination of IPA3 + indicated TKI for 24 hours in the presence of growth factor cocktail. (A-C) Indicated phosphoproteins were detected by FACS in annexin V–negative (A) Lin⁻CD34⁺CD38⁻CFSE^max/CTV^max quiescent LSCs, and (B-C) Lin⁻CD34⁺CD38⁻ LSCs. (D) ROS (H₂O₂ and ·OH) was measured by DCFDA. Results show mean ± SD from 4 to 5 patients; *, **, and ***P < .05 in comparison with normal cells, untreated CML-CP cells, and TKI-treated CML-CP cells using the Student t test.