Figure 3.

An extensive DNA damage is caused by treatment with PD166866. After treatment with the drug (50 μM for 24 hours), the cell nuclei were permeabilized. Fluorescent dUTP and terminal-deoxynucleotide-transferase were added. The enzyme conjugates the nucleotide where the sugar-phosphate backbone is interrupted. The high intensity of fluorescence (large panel) indicated of extensive DNA damage due to the exposure to the drug. This is also monitored in cells treated with H₂O₂ (small left panel), while it is virtually absent in untreated control cells (small right panel).