VEGF stimulates MEF2C-dependent gene expression. (A) HRECs were cotransfected with a minimal 3X-MEF2-firefly Luc-reporter and internal control pRL-SV40 containing the Renilla luciferase gene. The 3×-MEF2-firefly luciferase contains three copies of a high-affinity MEF2-binding site from the desmin promoter (desMEF2). After overnight incubation, cells were treated with VEGF (25 ng/mL), PlGF (25 ng/mL), FGF-2 (25 ng/mL), or erythropoietin (10 U/mL), then lysed for measurements of firefly and Renilla luciferase activity. All results are corrected for variations in transfection efficiency by normalization to expression of the cotransfected pRL-SV40 plasmid. Data are expressed relative to the luciferase activity observed in the control state (no VEGF treatment). (B) HRECs were cotransfected with 3X-MEF2-Luc reporter, internal control pRL-SV40 containing the Renilla luciferase gene, and MEF2C mutant expressing plasmid or control vector. After overnight incubation, cells were treated with VEGF (25 ng/mL) for 16 hours, then lysed for measurement of luciferase activity. *P < 0.05 compared with control pcDNA3.1. **P < 0.01 compared with control pcDNA3.1 in the presence of VEGF. (C) HRECs were cotransfected, as described, with 3X-MEF2-Luc and pRL-SV40. Cells were treated with the indicated doses of VEGF for 16 hours and then assayed for luciferase activity. (D) HRECs were cotransfected with 3X-MEF2-Luc and pRL-SV40. Cells were treated with VEGF (25 ng/mL) for the indicated times and then assayed for luciferase activity. *P < 0.05, **P < 0.01, and ***P < 0.001 versus control for (A), (C), and (D).