Using K14cre;Brca1F/F;Trp53F/F (KB1P) and K14cre;Brca2F/F;Trp53F/F (KB2P) genetically engineered mouse models of hereditary breast cancer [4, 5], we have identified various BRCA1- or BRCA2-independent mechanisms of PARPi resistance [reviewed in [6, 7]]. Here, BRCA1 is linked to breast cancer.