The hMutSα restores the repair of the G:G mismatches to the APE-expressing cells. ( A ) Purified hMutSα (hMSH2-hMSH6 heterodimer) was separated on a SDS–PAGE (8%), which was stained with Coomassie blue. The first lane of gel contains pre stained protein size marker (MBI, Fermentas), and the second lane contains hMSH6 (160 kDa) and hMSH2 (105 kDa). ( B ) The nuclear extracts of the control cells (637) and the APE expressing GM00637 cells (637 clone-3 and clone-7), and the HEC59 cells and its complementary cells were assayed for the repair of a G:G mispair in the presence or absence of 40 ng of the purified recombinant hMutSα. The results are based on counting 500–1000 plaques per variable. The repair efficiency was calculated as the percentage of decrease in the mixed-color colonies. The values are a mean ± SD from three separate experiments. Asterisk denotes P < 0.05.