FIG. 6.

UDG-BER activities for MGC nuclear extracts prepared from 3-month-old B6D2F₁ (open), 28-month-old B6D2F₁ (solid), and 3-month-old Apex heterozygous knockout mice (striped). Results are presented as means ± SEM of three replicate assays for each of three independent nuclear extract preparations. ∗, significantly (P < 0.05) different from addition of 0 ng of protein within a specific group. †, amount of purified APE/REF-1 required to restore activity to that of 3-month-old mice with 0 ng of protein added.