Role of RhoA/ROCK pathway and the actin cytoskeleton in thrombin-induced ICAM-1 expression in endothelial cells. Thrombin challenge of endothelial cells results in activation of RhoA/ROCK, which activates IKKβ to mediate the release of RelA/p65 secondary to phosphorylation and degradation of IκBα. RhoA/ROCK, in addition to activating IKKβ, induces a dynamic reorganization of the actin cytoskeleton. This event serves to promote the association of actin with the liberated RelA/p65, and this interaction, in turn, facilitates the translocation of RelA/p65 to the nucleus. The nuclear RelA/p65 binds to the promoter and induces the expression of ICAM-1.