ESR1 and cancer: In fact, it drives an increasein the intracellular concentration of reactive oxygen species (ROS),leading to the opening of the mitochondrial permeability transitionpore as well as altering the permeability of the mitochondrial membraneand stimulating cytochrome c release.31,51,52 Interestingly, tamoxifen exhibits ER-independentanticancer effects in various cancer cell types for which inductionof apoptosis through mitochondrial dysfunction has been advocatedas one of the mechanisms underlying such effects.53