INO80-C stimulates APE1 endonuclease activity.A, schematic showing the APE1 incision assay on the Fam-labeled (yellow star) 0N80 nucleosome. A red cross denotes the double THF on DNA at SHL-6 site. Substrate (S) and product (P) were separated in a denaturing gel. B, denaturing gel showing APE1 incision of nucleosome substrates with ATP present, without INO80-C (lane #1–6) and with INO80-C (lane #7–12). INO80-C alone (last lane) was assayed in the same condition. Each reaction was carried out with 100 nM nucleosome. APE1 and INO80-C concentrations were indicated. C, quantification of (B) as the percentage of DNA cleaved. Data are mean ± SD, n = 3. p value was shown. D, denaturing gel showing APE1 incision of the nucleosome substrate without ATP, without INO80-C (lane #1–6) and with INO80-C (lane #7–12). 100 nM nucleosome were used in each reaction. INO80-C alone (last lane) was also assayed in the same condition. E, quantification of (D) as the percentage of nucleosome DNA cleaved. Data are mean ± SD, n = 3. p value was indicated. F, denaturing gel showing APE1 incision reaction after APE1-INO80-C pre-treatment at 37 °C with ATP. 100 nM nucleosome were used in each reaction. G, quantification of (F). Data are mean ± SD, n = 3. p value was shown. H, denaturing gel showing APE1 incision reaction after APE1-INO80-C pre-treatment at 37 °C without ATP. 100 nM nucleosome were used in each reaction. I, quantification of (H). Data are mean ± SD, n = 3. p value was shown.