Effects of arsenite, hydrogen peroxide, and NONOate on DNA binding of purified PARP- 1. PARP-1 was isolated by immunoprecipitation from untreated HaCat cells, then the purified PARP-1 protein was treated with indicated concentrations of sodium arsenite, hydrogen peroxide, and NONOate for 48 hours at 4°C, and the DNA-binding ability was tested with EMSA as described in the legend to Fig. 4. Data are presented as means± S.D. * P<0.05 vs. concentration of 0 group, n=4. A) The images of EMSA. B) Effects of sodium arsenite. C) Effects of hydrogen peroxide. D) Effects of NONOate.