FACS analysis of Stat3 and Stat5 activity in ligand-stimulated primary AML cells. (A) Representative dot plots for a sample that responded to G-CSF (10 ng/mL; center) with increased pY-Stat3 and pY-Stat5, and to IL-6 + sIL-6R (5 + 10 ng/mL; right) with pY-Stat3 only. The unstimulated condition is shown for comparison (left). Waterfall plots illustrate the (B) pY-Stat3 responses to G-CSF, (C) pY-Stat5 responses to G-CSF, and (D) pY-Stat3 responses to IL-6 + sIL-6R, at the 3 doses tested. Data are expressed as the log₂(ΔMFI) of the stimulated condition over the unstimulated condition. Samples are arranged in ascending order by the log₂(ΔMFI) for dose level 3, and only those samples with a log₂(ΔMFI) ≥ 1 for at least 1 dose level are shown.