Effect of IM treatment on Bcr-Abl kinase activity and downstream signaling pathways in CD34⁺ cells expressing low and high levels of Bcr-Abl. CD34⁺GFP⁺ cells were cultured in SFM with low GF with 0, 0.1, and 1.0 μM IM for 16 hours, following which protein extracts were prepared and Western blotting was performed. In each case, blots were reprobed with antiactin antibodies to determine sample loading. Representative blots are shown. Cumulative results of densitometry from multiple experiments are shown in Tables 1–2. (A) Western blotting with antiphosphotyrosine antibodies. (B) Western blotting with anti–P-MAPK, anti–P-AKT, and anti–P-STAT5 antibodies. (C) Western blotting with anti–Bcl-X_S/L and anti–Mcl-1 antibodies.