Calcium mobilization induced by F peptide in phagocytes and attenuation by fMLF. Monocytes (A) or neutrophils (C) were loaded with Fura-2 and stimulated with different concentrations of F peptide. The ratio of fluorescence at 340 and 380 nm was recorded and calculated with the FLWinLab program. (B) and (D) show sequential stimulation of monocytes (B) or neutrophils (D) with fMLF and F peptide or vice versa.