As shown in Supplementary Fig. S1, when the viability of all cell lines was compared with vehicle at a fixed concentration of 250 nmol/L, MBQ-167 and MBQ-168 were not as potent in the ER/PR-positive MCF7 breast cancer cells and the noncancer MCF10A cells, demonstrating a 40% and 30% inhibition of cell viability, compared with 50% inhibition in MDA-MB-231 cells and approximately 85% in GFP-HER2-BM cells. Here, ERBB2 is linked to breast cancer.