D, E: or transfected with control, or FIP3.1 siRNA. Cells were allowed to form immunological synapses with SEE-pulsed Raji cells for 30 min. Intracellular distribution of endogenous Rac1 and surface distribution of CD3 were detected by immunofluorescence. 3D confocalimages were post-treated by deconvolution. A 0.4-µm-thick medial stack is shown. C, E: Population analyses of the amount of Rac1 at the immunological synapse relative to the total cellular Rac1. Each dot corresponds to one cell. Horizontal bars represent the mean ± SEM. Mann-Whitney test. Images are representative of three experiments. Bar, 5 µm. 