Figure 2: SupF forward mutation assay using a shuttle plasmid containing a single 8-hydroxyguanine (8OHG) in its supF gene. (A) Construction of a shuttle plasmid pMY189 [141] containing an 8OHG:C mispair at the specific position of supF [54,56]. 8OHG is shown in red. (B) Procedure for supF forward mutation assay. (C) A G:C to T:A mutation at the 8OHG-introduced position of the supF gene. A mutation at this position is frequently detected in assays using the in vitro synthesized shuttle plasmid shown in (A). The capacity of human cells to suppress the mutation caused by 8OHG can be evaluated under various conditions.