Figure 3: Transcriptional repression of HER2 by TPL. (a) SKOV-3 cells were treated with 50 nM of TPL and harvested at the indicated time. The quantitative PCR was performed as described in Section 2. (b) TPL inhibits neu promoter activity. For the luciferase assay, NIH3T3 cells were cotransfected with neu promoter luciferase (0.8 μg) and pCMV-β-gal (0.2 μg) plasmid DNA for 6 h and then treated with various concentrations of TPL for 24 h. The activity of luciferase in relative light units (RLUs) was normalized against β-gal activity. (c) The pGL4-HER2-F1-Luc through pGL4-HER2-F4-Luc constructs were transfected into NIH3T3 cells for 6 h, and then 50 nM TPL was added for 24 h. The RLUs were determined as above. TPL downregulated reporter expression at the HER2 F4 (from −207 to −103) region.