PARP1 and breast cancer: Next, we evaluated PARP‐1 inhibition effect on oxidative DNA damage in Ets‐1‐overexpressing and Ets‐1‐non‐expressing breast cancer cells and we showed that PARPi led only Ets‐1‐overexpressing cells to accumulate it, which triggers the DNA damage response as revealed by the increase in the level of a panel of DNA damage‐related proteins.