Fig. 6. Cdc42 and Rac1 activation by uPA and EGF. (A,B) Cells were assayed for Cdc42/Rac1 GTPase activation using a PAK-CRIB pull down assay. The levels of total cellular Rac1/Cdc42 and GST-PAK-CRIB that precipitated Cdc42/Rac1 were determined by SDS PAGE on 12% gels and immunoblotting. Temporal activation of (A) Cdc42 and (B) Rac1 by 10 nM uPA and 10 ng/ml EGF are shown. Graphs show ratios of GST-PAK-CRIB bound to total Cdc42/Rac1 (band intensity in unstimulated cells, 1.0). The results represent mean±s.e.m. from three to seven experiments.