Figure 6.

Adhesion (Adh) of neutrophils to fibronectin (FN) or fibrinogen (Fg) leads to delayed Rac2 and Vav1 activation in response to fMLF or C5a stimulation. Neutrophils plated on fibronectin (50 μg/ml), fibrinogen (20 μg/ml), or in nonadherent (Sus) conditions were treated with 1 × 10^–7 M fMLF or 10 nM C5a. After 5 minutes, Rac2 (a) and Vav1 (b) activities were determined, as described in Methods. Total Rac2 and Vav1 levels (anti-Rac2 and anti-Vav1 IB) were constant under each condition. The results shown are representative of two similar experiments obtained with cells derived from different donors.