FIG. 3.

Inhibition of DNA synthesis is inversely related to stabilization of cleavable complexes in the cell. Each point is a single compound whose ability to promote cleavable complex formation in situ was evaluated at 5 μM. If compound 13 (▪) is excluded from the analysis, the fitted line follows the equation y = 80 − 3.8x, and R² = 0.88. In these experiments, the positive control camptothecin at 10 μM trapped 61 ± 8% of radiolabeled DNA in covalent protein-DNA adducts and inhibited DNA synthesis at 27 ± 5%. Standard deviation values are reported in Table 4.