Figure 7.

a) Concentration–effect relationships for the enhancement of secretion by Rac2 (preactivated by binding of GTPγS) in mast cells stimulated by Ca²⁺ plus GTPγS (100 μM). In this experiment, the cells were run down for 17 min before application of the stimulus. (a) Results are expressed as means ± SEM (n = 4). •, Cells stimulated with Ca²⁺ (pCa5) and GTPγS (100 μM); □, unstimulated cells. (b) Data of Figure 6a presented as a Hill plot. For secretion stimulated by Ca²⁺ plus GTPγS, slope p = 1.6 (r = 0.99, n = 5 data points). Similar results were obtained on four separate occasions.