Fig. 4. Rac is involved in cortactin relocalization. HUVECs were electroporated with the pMT90-myc Rac1 N17 expression vector. Eighteen hours after electroporation, cells were detached, plated onto fibronectin-coated coverslips and allowed to spread for 8 hours before overnight serum starvation. Cells were then stimulated for 2 minutes with 0.5 µM S1P, fixed and stained for detection of myc expression (left panel) and cortactin localization (right panel). Arrows show myc-tagged RacN17-expressing cells.