Fig. 4. MSH2-independent A/C repair does not require MutLα. (A) A/C repair activity in Mlh1 nullizygous MC2 cells. A/C repair assays were carried out using extracts of MC2 (Mlh1^–/–) and the parental wild-type MC5 cells. The repair products (arrowed in the gel photograph) were analysed by agarose gel electrophoresis and quantified as described in Materials and methods. MC2 (▪); MC5 (□); RH95021 (○). (B) Effects of neutralizing antibodies against PMS2 on A/C repair in extracts of RH95021 and Colo26 cells. RH95021 (▪, □) or Colo26 (•, ○) extracts were pre-incubated with the increasing amounts of IgG shown before addition of the mismatched DNA. After a standard repair reaction, products were analysed and quantified. Anti-PMS2 antibody (▪, •); non-specific IgG (□, ○).