T3s display high affinity for ERβ and increase its translocation into the nucleus which, in turn, activates the expression of estrogen-responsive genes [MIC-1 (macrophage inhibitory cytokine-1), EGR-1 (early growth response protein 1), and cathepsin D] involved in growth arrest, altered morphology, and apoptosis of ERβ expressing breast cancer cells (MDA-MB-231 and MCF-7) [78]. Here, EGR1 is linked to breast cancer.