Endocytosis: RasGAPs Help Organize Macropinocytic Cups.

Macropinocytic cups enable cells to take up droplets of medium into internal vesicles. These cups are formed by the actin cytoskeleton around signaling patches of Ras, Rac and the phosphoinositide PIP3 in the plasma membrane. New work now describes a Ras regulator that controls both the size and efficiency of these patches.