Surprisingly, the expression of KLF4 was significantly correlated with the expression of PARP1 and vice versa in breast cancer tissues, which indicates that KLF4 and PARP1 are co‐accumulated in most breast cancer tissue including TNBC, HER2‐positive, and ER/PR‐positive breast cancer (Fig 3C–H). Here, ESR1 is linked to breast cancer.