Fig. 5.

Mutation of the catalytic arginine of the GAP domain of RhoGAP22 potentiates growth factor-stimulated Rac-GTP loading. (A) NIH 3T3 fibroblasts expressing various RhoGAP22 constructs (described in the text) were serum starved and treated with 20 ng/ml PDGF for 5 min or left untreated. Cells were lysed, subjected to PAK-GST pulldown, and blotted with indicated antibodies. (B) The induction of Rac-GTP loading for each cell line was determined via densitometry. Error bars indicate standard deviations of the means. Significance was determined using Student's unpaired t test. *, P < 0.05; **, P < 0.01.