Figure 7. Actin polymerization is not needed for uniform but for polarized PIP₃ production.

(A) Schematic representation of experiments conducted in (B)–(E). (B) Ratio images (YFP-PH(AKT)/CF-iSH ) showing the suppression of polarized PIP₃ accumulation in the front by LatA addition. LatA was added to cells in which PI3K was already synthetically activated. (C) Linescan intensity analysis along the plasma membrane region before (black line) and after (red line) LatA addition. (D) Time series showing that synthetic PI3K activation fails to generate polarized PIP₃ in the presence of LatA. (E) Quantification of the imaging results, showing that LatA completely suppresses PI3K-induced cell migration. Error bars are given in S.E.M. (n = 15 from three independent experiments).