ESR1 and breast cancer: There is strong evidence for the anti-proliferative effects of γ-T3 on breast cancer cell lines MDA-MB-231 (IC50 11.4 μM), MCF-7 (IC50 15.4 μM) (Loganathan et al., 2013), SKBR3 (IC50 4 μM), BT474 (IC50 4 μM) (Alawin et al., 2016), estrogen receptor-negative MDA-MB (IC50 73.2 μM), and estrogen receptor-positive MCF-7 cells (IC50 4.9 μM) (Guthrie et al., 1997).