Hydrogen peroxide treatment decreases in vivo Sp1 binding to MYC and C17 promoters. (A) ChIP assay showed decrease of Sp1 binding on the promoters of c-Myc and C17 after oxidation by hydrogen peroxide treatment. (B) Cell fractionation after hydrogen peroxide treatment showed no decrease in the level of Sp1, which was exclusively nuclear. Cytosolic heat shock protein 90 (Hsp90) was used as a control for fractionation. γ-Tubulin was used as a loading control.