Dose-dependent effect of PlGF on the chemotaxis of THP-1 monocytes. (A) THP-1 cells (5 × 10³ cells) were added to the upper compartment of a Neuro Probe chemotaxis chamber. The indicated concentrations of either PlGF and/or MCP-1 were added to the lower compartments, the chambers were incubated for 2 hours at 37°C, and then the migrated cells were stained and counted as described in the text. Results show mean ± SD of 4 independent experiments. (B) For inhibitor studies, THP-1 monocytes were pretreated with the respective pharmacologic inhibitors or antibody for 30 minutes. THP-1 cells transfected with the dominant-negative mutants of AKT and PI3 kinase were also used for the chemotaxis assay.