Fig. 4.

PIP₃ localization and its content. (A) Localization of PIP₃ in p55^−/− neutrophils. A monoclonal anti-PIP3 antibody was used to stain PIP₃ in resting and activated WT and p55^−/− neutrophils. In resting cells, there was a faint signal of PIP₃ around the peripheral membrane. Upon stimulation with fMLP, WT neutrophils polarized by accumulating PIP₃ toward the leading edge membrane marked by F-actin staining. Upon stimulation, p55^−/− neutrophils formed extensions but PIP₃ is diffusely localized throughout the cytosol. (B) Neutrophils were incubated with anti-PIP₃ antibody and FACS analysis was performed to measure total PIP₃ levels after fMLP stimulation. No difference in total PIP₃ was observed between WT and p55^−/− neutrophils. Two independent experiments are shown.