Figure 4.

Functional significance of HMGA1 for IGFBP-3 gene transcription. HepG2 cells were transfected with the pGL3-IGFBP-3 Luc reporter plasmid (1 μg) in the presence of the indicated effector vectors (0.5 μg each, black columns). Empty column indicates mock (no DNA). Functional analysis with small interfering RNA directed against HMGA1 (100 pmol) is shown in the gray column. Transcriptional activity of the IGFBP-3 promoter is shown as the ratio of Luc activity to Renilla activity (Luc/Ren). Columns indicate mean values; error bars denote standard deviation. There were three separate experiments. *P = 0.03; **P < 0.0001; ***P < 0.0001. C/EBPβ, CAAT-enhancer binding protein β; HMGA1, high-mobility group A1; IGFBP-3, insulin-like growth factor binding protein 3.