ESR1 and cancer: To compare the antitumor and cytotoxic effects of the isolated compounds (aloe emodin, rhapontigenin, and chrysophanol 1-O-β-d-glucopyranoside), two different breast cancer cell lines, namely, MCF-7 (low-invasive, ER-negative, estrogen-independent cancer cells) and MDA-MB-231 (highly invasive, ER-positive, estrogen-dependent cancer cells) were used in the present study [7,29,30].