BRCA1 and triple-negative breast carcinoma: To assess this, we carried out a focused small-interfering RNA (siRNA) screen to identify synthetic lethal (SL) interactions between nucleic acid sensing PRR and BRCA1. In this screen, we used a BRCA1-isogenic system consisting of the BRCA1-mutant (c.2288delT, p.N723fsX13), SUM149 triple-negative breast cancer (TNBC) cell line (SUM149 BRCA1-Mut) and a previously described daughter clone, SUM149 BRCA1-Rev, with a secondary reversion mutation in BRCA1 (c.[2288delT;2293del80]) that restores BRCA1 function22 and PARPi resistance (Fig. 1A, and Supplementary Fig. 1A).