Table 1. Initial adduct levels.

Genotype	Average number of adducts/cell
	3MeA	7MeG	O6MeG
Aag+/+	1.2 × 105	3.5 × 106	2.6 × 105
Aag–/–	2.2 × 105	4.1 × 106	2.4 × 105

Aag^+/+ and Aag^–/– mouse ES cells were exposed to [³H]MNU and subsequently assayed for 3MeA, 7MeG and O⁶MeG as described in Materials and Methods. Calculations are based on an average of 1.5n DNA content. All values are approximated from the average of between three and six experiments.