In this study, we examined the effect of four PARPi, PJ‐34, ABT‐888, olaparib, and rucaparib in two breast cancer cell lines without BRCA mutation, Ets‐1‐expressing MDA‐MB‐231, and Ets‐1‐non‐expressing MCF‐7. Here, ETS1 is linked to breast cancer.