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. 2006 Jun 14;397(Pt 1):169–177. doi: 10.1042/BJ20051669

Figure 4. Transcriptional repressor activity is mediated through the INSM1 binding site.

Figure 4

A triple repeat of the INSM1 binding site was cloned into an E1bTATA-basic promoter driven luciferase reporter gene. Transfection experiments were performed in HEK-293 cells as described above, in order to identify the repressive activity of INSM1, cyclin D1 or both. INSM1 demonstrated a 50% repressive effect, whereas cyclin D1 failed to suppress the E1bTATA promoter. A combination of INSM1 and cyclin D1 enhanced suppressive activity by up to 60% (*P<0.05). This result revealed that the INSM1 binding site is crucial for cyclin D1 to co-operate with INSM1 for transcriptional repression. A CMV-β-galactosidase construct was used to normalize transfection efficiency. The histogram shows the means for four separate experiments±S.E.M. A representative Western blot of the expressed proteins is shown below the chart.