Antiproliferative activity induced by 2-methoxyestradiol-bis-sulphamate was detected in the estrogen receptor positive human breast adenocarcinoma MCF-7 cell line (0.1–1 μM), prostate cancer cell line (LNACaP), tumorigenic estrogen receptor negative breast adenocarcinoma cell line (MDA-MB-231), esophageal carcinoma SNO cells, HeLa and the CAL51 human breast carcinoma cell line [26], [27], [28], [29], [30], [31], [32], [33]. This evidence concerns the gene ESR1 and breast adenocarcinoma.