Figure 4.

Alkaline-agarose gel electrophoresis of CHO-B11 cell DNA incubated with DB[a,l]P in the presence of HRP/H₂O₂. The reaction mixture was incubated for 1 hr at 37°C (see Materials and Methods). (A) KpnI-restricted DNA: no DB[a,l]P (lane 1); reacted with 20, 40, or 80 μM DB[a,l]P (lanes 3–7; without and with methoxyamine treatment). (B) Intensity of the 14-kb band of the DHFR gene of the DNA samples. All band intensities were normalized for the efficiency of sample loading on the gel through the use of a plasmid loading control.