Recruitment of Sac2 to macropinosomes. Mouse fibroblasts expressing GFP-Sac2 and either RFP-PH^AKT (A) or RFP-EEA1 (B) were also cotransfected with H-Ras^V12G to induce the formation of macropinosomes. The gallery of confocal images shows that Sac2 is recruited to these vesicles when the AKT signal, which primarily reflects PI(3,4,5)P₃, is disappearing, and remains associated with the vesicles as they mature to EEA1-positive endosomes. Bars, 1 µm.