Fig. 7. Effect of TPA and mßCD on the activation state of Rac 1. A431 cells were serum-starved in the presence of 0.5 mCi/ml [³²P]orthophosphate to label endogenous pools of GTP and GDP, and then incubated with or without 5 mM mßCD for 30 minutes at 37°C prior to addition of 0.5 µM TPA. After lysis of the cells with detergent, Rac 1 was immunoprecipitated and ³²P-labelled nucleotides bound to Rac 1 analyzed by TLC as described in Materials and Methods. The error bars show deviations (s.d.) between three independent experiments.