Adhesion of HL-60 promyelocytes to COS cells transfected with murine E-selectin. CFDA-labeled HL-60 cells were incubated with E-selectin–transfected COS cells in the presence of E-selectin MoAbs 10E9.6, 9A9, 10E6, or P-selectin MoAb 10A10. Adhesion was quantified by measuring the fluorescence intensity of the supernatant obtained after lysis of labeled HL-60 cells bound to E-selectin–transfected COS cells. The level of HL-60 cell adhesion to untransfected COS cells is indicated by the broken line. Average ± SEM of four experiments.