Fig. 10. Rac1 localization at nascent cell-cell contacts is dependent on PI 3-kinase signaling. HT-29 cells were cultured for 24 hours on laminin 5 matrix and then treated with 4 mM EGTA for 30 minutes in the absence or presence of 50 µM LY294002. The EGTA-containing medium was then replaced by Ca²⁺-containing medium for 60 minutes. Cells were fixed and stained for Rac1 before confocal microscopy analysis on optical sections. Bars, 25 µm.