Zn²⁺-induced adhesion of U937 cells on FBG. (A) Adhesion of U937 cells on FBG-coated plates induced by 50 μmol/L Zn²⁺ (○) or 20 ng/mL PMA (•) in the absence or presence of various concentrations of 1-10-phenanthroline was measured. Data represent the mean ± SEM (n = 3) of a typical experiment. The basal adhesion in the absence of PMA or Zn²⁺ was 0.05 to 0.1 absorbance units. Similar results were obtained in three separate experiments. (B) The adhesion of U937 cells on FBG induced by 50 μmol/L Zn²⁺ or 20 ng/mL PMA was measured in the absence (▩) or presence of 10 μg/mL MoAb 60.3 against β₂-integrin (▨). Data represent the mean ± SEM (n = 3) of a typical experiment. Similar results were obtained in three separate experiments.