FACS analysis of Stat3 and Stat5 activity in unstimulated primary AML cells. (A) Representative example of data analysis. (Left) Fifty-five samples were additionally stained for CD45, allowing estimation of the blast percentage and exclusion of residual lymphocytes. (Right) Unstimulated cells had variable percentages of events in the pY-Stat3⁺ regions (top and bottom right quadrants) and pY-Stat5⁺ regions (top left and right quadrants). (B-D) Waterfall plots illustrate the distributions of values for baseline phosphorylated Stat3 and Stat5. The red bars with asterisks indicate the values for 9 normal bone marrow samples that were analyzed similarly. Values represent the percentage of events in the positive region.