Figure 1. Cdc42 activity is increased upon Ras-mediated transformation.

(a) Cell immortalization was achieved following retroviral transduction of cdc42^f/f cells with a dominant-negative p53 (p53dd). Dominant-negative expression was determined by western blot for p53. (b) Immortalized, cdc42^f/f cells were transformed through retroviral transduction with HRasV12. Transformed cells exhibit HRas overexpression and increased active, GTP-bound HRas as determined by pull-down with the ras binding domain (RBD) of Raf1 fused to GST. (c) HRasV12 transformed cells exhibit a significant increase in Cdc42 activity compared to non-transformed control cells. Pull-down assays were performed with GST-PAK1. The graphed data represents densitometry quantification from three independent experiments.