D: Transfected Jurkat T cells were allowed to spread on anti-CD3-coated coverslips for the indicated time, and F-actin was detected with FITC-Phalloidin. A single optical section at the level of the contact surface is shown. E, F: Population analyses of the spreading area of cells at the level of the contact surface. Each dot corresponds to one cell. Horizontal bars represent the mean ± SEM. Mann-Whitney test. Images are representative of three experiments. Bar, 5 µm. 