Figure 3.

Identification of SP4 as a transcription factor mediating human VEGF promoter induction by the IL-6 + sIL-6R complex. (A and B) Cells were stimulated with IL-6 + sIL-6R at 100 ng/ml for 6 hours, and the nuclear fractions were obtained and analyzed with EMSA. In A, EMSA was performed with consensus oligonucleotide probes for SP1 and SP4. In B, formation of nuclear complexes with SP4 probe was assessed in the presence of either 100-fold molar excess of unlabeled VEGF DNA (resulting in a reduced shift) or SP4-specific antibody (resulting in supershift). (C) Effect of site-directed mutagenesis in the SP4 binding site within the VEGF promoter on its activity after stimulation with IL-6 + sIL-6R. Luciferase activity was expressed as relative light units (RLU). *P<0.05 versus relevant control (n=4).