ESR1 and triple-negative breast carcinoma: An ER-independent mechanism of action is also supported by their nanomolar IC50-values (380–970 nM) in all three types of triple-negative breast cancer cells (MDA-MB-231, MDA-MB-468 and BT-549 and by very similar IC50-values of the respective non-hydroxylated analogs 2a and 2b in all cancer cell lines including ER-positive MCF-7 cells.