NQO1 and breast cancer: We evaluate the effect of FRV–1, FRV–2, and methyl-analogs on the viability of breast fibroblast RMF-621 and two breast cancer cell lines: MCF7 (naphthoquinone oxidoreductase 1, NQO1 positive) and MDA-MB-231 (NQO1 negative) [42].