ESR1 and breast cancer: In contrast, in MDA-MB-231 cells (Figure 3G–H), used as a model of triple-negative BC, MC3324 did not induce cell death, but only a weak cell cycle perturbation and S phase accumulation, underscoring the importance of ERα to achieve epigenetic rebalance, possibly via activation of the intracellular cascade in which ERα is, both, effector and target.