Effect of HU and BAY73-6691 treatment on leukocyte activation and survival of TNF-α–treated SCD mice. (A) Quantification of RBC-WBC interactions, n = 5-7 mice per group (*P < .05 compared with vehicle). (B) Mac-1 integrin activity on adherent leukocytes as assessed by capture of fluorescent microspheres, n = 3 to 5 mice per group (**P < .01 compared with vehicle, Mann-Whitney test). Representative images of fluorescent spheres bound to adherent leukocytes after treatment with vehicle (C) or HU and BAY-73-6691 (D). The white arrow indicates the direction of blood flow. (E) Kaplan-Meier survival curve after treatment with HU and BAY73-6691 or vehicle. Log-rank (Mantel-Cox) test (*P < .05 compared with vehicle, n = 5-7 mice per group). Scale bar: 10 μm.