Platelet-derived growth factor (PDGF)-BB-induced monocyte transmigration and permeability is mediated by monocyte chemoattractant protein 1 (MCP-1). Human brain microvascular endothelial cells (HBMECs) were exposed for 24 h to supernatants from A172 cells treated with PDGF-BB with or without STI-571. MCP-1 neutralizing antibody was added to PDGF-BB-treated media prior to HBMEC exposure for 24 h. Human monocytes were added to the top transwell for 24 h followed by assessment of transmigration. Exposure of HBMECs to supernatants from A172 cells treated with PDGF-BB resulted in increased permeability and enhanced monocyte transmigration, which was abrogated by MCP-1 neutralizing antibody. All the data are presented as mean ± SD of three individual experiments. ***P <0.001 versus control group; ##P <0.01, ###P <0.001 versus PDGF-BB-treated group.