ESR1 and breast cancer: Treatment of a panel of breast cancer cell lines with 5 μM ABT-737 (Figure 7C) by using sub-IC50 concentrations of TRAIL, enhanced TRAIL-induced toxicity in all of the breast cancer subtypes tested (TNBC/Basal B, TNBC/Basal A, HER2 amplified, and ER + breast cancer) (Figure 7C).