GM-CSF–driven NF-κB signaling drives the formation of AML-exposed neutrophils. (A) Representative histograms of CD14 surface expression in BM neutrophils from healthy and AML mice. (B) Representative histograms of CD14 surface expression in blood neutrophils from healthy and AML mice. (C) Quantification of frequency of CD14⁺ neutrophils from total neutrophils in healthy and AML mice (n > 3). (D) Simple linear regression displaying positive correlation (r = 0.72; P < .05) between WBC count and frequency of CD14⁺ neutrophils as a percentage of total neutrophils in the blood of our AML mouse model (n > 10). (E) Western blot measuring C/EBPβ expression in sorted healthy and AML-exposed neutrophils. (F) Representative histogram of CD14 in our ex vivo cultures. (G) Quantification of CD14 expression in our ex vivo cultures (n > 3). (H) Representative histogram of CD101 in our ex vivo cultures. (I) Quantification of CD101 expression in our ex vivo cultures (n > 3). (J) Representative histogram of SSC in our ex vivo cultures. (K) Quantification of SSC expression in our ex vivo cultures (n > 3). (L) Western blot measuring C/EBPβ expression in ex vivo cultures. (M) Quantification of CD14 expression after 24 hours in various neutrophil and AML blast coculture conditions (n = 3). Significance is denoted as ∗∗∗∗P ≤ .0001 (unpaired 2-tailed t test for panel C); ∗∗∗P ≤ .001 (1-way ANOVA for panels G-K); ∗∗∗P ≤ .001; ∗∗P ≤ .01; ns P > .05 (2-way ANOVA for panel M); P ≤ .05 (simple linear regression test for panel D).