Cotransfection with an EGR-1 expression vector leads to a specific activation of the flt-1 promoter.

HUVEC were transiently cotransfected with pFlt-1–Luc in (A), p3EGR–Luc (both described in Figure 3) or the AP-1–dependent transcription reporter plasmid 2XAP-1–Luc in (B), together with an Egr-1 expression vector driven by the SV40 promoter (pBXEGR-1) or the empty vector (pBX). When indicated, cells were treated with PMA 50 ng/mL for 8 hours before measuring luciferase activity. The number of experiments, normalization, and statistics are similar to those in Figure 3.