Elevated CXCL1 expression in cultured gp130-deficient endothelial cells increases neutrophil arrest but impairs neutrophil transendothelial migration. Cultured lung endothelial cells from WT or EHCgp130^−/− mice were left unstimulated (basal) or stimulated with TNF-α for 4 hours. (A) Levels of the indicated proteins were measured by immunoblotting of cell lysates. (B) Relative CXCL1 mRNA in unstimulated and TNF-α–stimulated endothelial cells was measured by reverse-transcriptase polymerase chain reaction. (C) CXCL1 protein in unstimulated endothelial cells was measured by ELISA. (D-F) Numbers of WT neutrophils rolling or firmly adherent (arrest) on monolayers of TNF-α–stimulated endothelial cells from WT or EHCgp130^−/− mice. As indicated, some cells were pretreated with PTx or with anti-CXCR2 or anti-CXCL1 mAb. (G) Monolayers of lung endothelial cells (EC) of the indicated genotype cultured on transwell filters were stimulated with TNF-α. Neutrophils of the indicated genotype were added to the upper compartment, and CXCL1 at the indicated concentration was added to the lower compartment. After 60 minutes, the number of neutrophils migrating into the lower compartment was measured. The data in (A) are representative of 3 independent experiments. The data in (B-C) represent the mean ± SEM from 6 mice in each group. The data in (D-G) represent the mean ± SEM from 3 experiments. *P < .05.