FIG. 6.

SEE-induced Cdc42 activation at the IS with Raji APC. Jurkat T cells (WT or A1-derived lines) expressing the Raichu-Cdc42 plasmid were added to Raji B cells either preloaded with SEE superantigen (+SEE) or unloaded as a control (−SEE). WT Jurkat cells transfected with the T17N mutant form of Raichu-Cdc42 provide the baseline control. Target cells were labeled for 15 min at 37°C with 20 μM CMTMR (orange cell tracking dye; Molecular Probes). The mRFP1 emission was not visible at the set exposure time for the red channel, which was kept at a minimum because of the brightness of the CMTMR labeling. Bar charts represent the cumulative data of four experiments (n = 15 cells) for Raichu-Cdc42 (*, P < 0.05; **, P < 0.005; both by t test). Scale bar = 5 μm.