Effect of P2Y6 receptor antagonist MRS 2578 on endothelial NF-κB activity. To measure the NF-κB activity, vascular endothelia (HMEC-1) were transfected with 0.25 μg of either NF-κB promoter reporter (Clontech) or control pGL3 vector. Cells were exposed to the P2Y6 receptor antagonist MRS 2578 either with or without TNF-α for the indicated time periods. As readout for NF-κB activity cells were lysed, and luciferase activity was determined relative to the total protein concentration. (A-B) Unstimulated NF-κB activity after exposure to indicated times or concentrations of MRS 2578. (C) NF-κB activity after stimulation with MRS 2578 (30 minutes) and after stimulation with TNF-α (10 ng/mL) for 2 hours. Results are displayed as mean ± SD (n = 3).