Figure 4.

Nogalamycin increases Sp1 binding to a GC-rich oligonucleotide probe. ³²P-labelled oligonucleotide bearing consensus elements for Sp1, Egr-1 and Sp3 (³²P-Oligo A, 5′-GGG GGG GGC GGG GGC GGG GGC GGG GGA GG-3′, two overlapping consensus Egr-1 binding sites italicised). (A) EMSA was performed as described in Materials and Methods. Supershift analysis shows a distinct pattern of nucleoprotein complexes (Sp1, Egr-1, Sp3), whereas competition analysis demonstrates the specificity of these complexes. (B) Densitometric quantitation of band intensity from EMSA. (C) Western blot analysis for AP2 using the same extracts as those used for the EMSA. The data are representative of two independent determinations.