Figure 1.

Influence of topoisomerase I on the sequence-specific binding of p53 as measured by an electrophoretic mobility-shift assay. All lanes contained radiolabeled oligonucleotides carrying the p53-binding site of the GADD45 promoter. Lanes 2–5 and 6–9 contained 500 ng of p53 or 500 ng of p53–GST, respectively, in the presence of 1 μg of PAb 421 (lanes 3, 5, 7, and 9) or 500 ng of topoisomerase I (lanes 4, 5, 8, and 9). As control, oligonucleotides were incubated in the absence of p53 either alone (lane1), with topoisomerase I (lane 10), with PAb 421 (lane 11), or in the presence of both topoisomerase I and PAb 421 (lane12).