PAF selectively activates Rho GTPase Rac1. A, Rac1 is the
only small GTPase activated. Western blot shown in the upper panel
demonstrates the activation of Rac1 after PAF treatment, whereas the lower
panel shows that the total amount of Rac1 is not modified (n =
10). Note that Rac1 activation returns to basal level by 30 min. Quantitative
measurements are shown in the associated bar graph. B, RhoA was not
activated, as shown by the Western blot from the upper panel. The
lower panel illustrates that the total amount of RhoA present in the
monolayers did not change. Summary data from different experiments are
presented in the bar graph (n = 5). Note the changes in the
status of RhoA after thrombin (10 IU, 30 min), its bigger activation after
sphingosine 1-phosphate (5 μm, 15 min), and its unchanged status
after PAF. C, Cdc42 was also not activated at any time point after
PAF challenge (n = 5), and the total levels remained relatively
unchanged, as shown in the lower panel. The summary bar
graph represents studies in confluent monolayers. Statistical
significance for A-C is as follows: *, p <
0.01; **, p < 0.05; ‡, p < 0.001
(paired Student's t test).