p130Cas and Crk are required for Rac activation and invasion in uPAR-expressing tumor cell lines. (A) BE cells (closed bars) and SNB19 cells (shaded bars) were transfected with siRNAs, and Rac activation was quantitated as described in Fig. 2 (mean + SEM; n ≥ 5). **, P < 0.01; unpaired Student's t test. (B) BE cells were transfected with siRNAs, and the association of p130Cas with DOCK180 was determined by immunoprecipitation of DOCK180 and immunoblotting for p130Cas. Immunoblots are representative of three independent experiments. (C) BE cells were transfected with siRNAs. At 60 h after transfection, cells were assayed for collagen-I invasion (mean + SEM; n ≥ 4). *, P < 0.05; **, P < 0.01; unpaired Student's t test. Immunoblots showing knockdown are in Fig. S2 B.