p130Cas and Crk are required for uPAR-stimulated Rac activation in HEK 293T cells. HEK 293T cells were transfected with siRNAs. 48 h after siRNA transfection cells were transfected with uPAR expression vector or empty vector control (Vec). 24 h later (72 h after siRNA transfection), Rac pull-down assays were performed. (A) Representative immunoblots from one experiment. (B) Quantitation of Rac activation (mean + SEM; n = 3). *, P < 0.05; **, P < 0.01; unpaired Student's t test. (C) Representative immunoblots of silencing p130Cas and CrkII at 72 h after transfection.