Hy 10129

All IBC cell lines were grown in HAMS F12 media (Gibco 11765–054) in a 5% CO₂ incubator. Media for SUM-149 cells was supplemented with 5% FBS (Atlanta Biologicals), 10mM HEPES (Thermo Fisher 15630080), 1x antibiotic-antimycotic (anti-anti, Thermo Fisher 15240062), 1μg/mL hydrocortisone (Sigma H4001), and 5μg/mL insulin (Sigma I9278). SUM-190 media was supplemented with 1% FBS, 1μg/mL hydrocortisone, 5μg/mL insulin (Sigma I0516), 50nM sodium selenite (Sigma S9133), 5μg/mL apo-Transferrin (Sigma T-8158), 10nM triiodo thyronine (T3, Sigma T5516), 10mM HEPES, and 0.03% ethanolamine (Sigma 411000). MDA-IBC-3 cells were grown with 10% FBS, 1μg/mL hydrocortisone, 1x anti-anti, and 5μg/mL insulin (Sigma I0516). SUM cell lines were obtained from Stephen Ethier at the Medical University of South Carolina, and MDA-IBC-3 cells were obtained directly from Wendy Woodward at the University of Texas MD Anderson Cancer Center. All cell lines were routinely tested for mycoplasma contamination (Lonza LT07–418) and were authenticated using fragment analysis at the University of Michigan DNA sequencing core. Olaparib (MedChem Express HY-10162) and veliparib (MedChem Express HY-10129) were reconstituted in 100% DMSO for cellular assays.