ATF4 regulates MCP-1 expression through enhancing NF-κB and MAPK activation. A). Brain endothelial cells from ATF4 +/+ and ATF4 −/− mice were treated with 250 ng/ml LPS for 8 h. The levels of p-NF-κB, p-P38, p-JNK, p-P42/44 were determined by western blot analysis and quantified by densitometry (mean ± SD, n = 3). *P < 0.05 vs. WT; +P < 0.05, ++P < 0.01 vs. WT + LPS. B). Brain endothelial cells from ATF4 +/+ mice were pretreated with 1 μM Ro106, 10 μM SB203580, 10 μM SP600125 or 10 μM U0126 for 1 h, followed by transduction with Ad-ATF4 or Ad-Ctrl for 24 h. MCP-1 protein levels in the media were measured by ELISA. Results are expressed as mean ± SD (n = 3). ** P < 0.01 vs. Ad-Ctrl; + P < 0.05, ++ P < 0.01 vs. Ad-ATF4.