Typical traces showing the effect of Ro 31-8220 and staurosporine on intracellular calcium transients induced by a maximally effective concentration of LTB₄. Eosinophils were labeled with fura-2-acetoxymethyl ester and washed and changes in fluorescence were monitored. The cells were pretreated for 3 minutes with vehicle, Ro 31-8220 (3 × 10⁻⁵ mol/L), or staurosporine (10⁻⁷ mol/L) before the addition of LTB₄ (10⁻⁸ mol/L, shown by the arrows). Results are expressed as the increase in intracellular calcium in nanomoles per liter as a function of time (in seconds).