FIG. 3.

The Sp1 sites, located between positions −194 and −51, are involved in Tax 1-mediated downregulation of the VEGF promoter. 293T (a) and Jurkat (b) cells were cotransfected with PGL3-2.6, PGL3-1.5, or PGL3-320, the internal control pRLTK, and either the Tax expression plasmid pCA-Tax 1-HIS or empty pCA vector. Luciferase activity was quantified after 48 h and was normalized to TK activity. Basal activity was constant for all of the reporters and was set at 100%. Differences in normalized luciferase activity were significant as determined by Student's t test. (c) 293T cells were cotransfected with the indicated concentrations of pCA-Tax 1-HIS or empty pCA vector together with the PDGF luciferase reporter pRALuc (35) and the internal control pRLTK. Luciferase activity was quantified after 24 h and was normalized to TK activity. Basal activity was set at 100%.