Figure 6.

Concentration–effect relationships for the enhancement by (a) Rac2 and (b) Cdc42/G25K (preactivated by binding of GTPγS) in mast cells stimulated by Ca²⁺ alone. In this experiment, the cells were run down for 7 min before the stimulus was applied. Protein concentrations, expressed as active protein binding [³H]-GTP, were applied according to a ×2 serial dilution scheme. Results are expressed as means ± SEM (n = 4). Similar results were obtained on four separate occasions (Rac) and on nine occasions (Cdc42). ▴, Cells stimulated with Ca²⁺ (pCa5); □, unstimulated cells.