FIG. 4.

Signaling events activated by ICAM-1 engagement during leukocyte adhesion. Ligation of ICAM-1 induces a variety of responses in endothelial cells. These include RhoA activation, ERK, and JNK activation, ROS generation, and Src activation. Activated RhoA and ROS/Src, through activation of downstream effectors, induce reorganization of the actin cytoskeleton. ERK and JNK causes AP-1 (Jun/Fos) activation and gene expression including ICAM-1, suggesting the possibility of a feed-forward mechanism whereby ligation of ICAM-1 increases its own expression to amplify the adhesion and TEM of leukocytes to the site of inflammation.