evealed increased caspase-8 activity comparable to that of cells treated with 2-methoxyestradiol-bis-sulphamate and actinomycin D. Caspase-6 colorimetric studies demonstrated an increased caspase-6 activity in compound-treated cells when compared to vehicle-treated cells. Caspase-6 activity of cells treated with ESE-16 increased to 3.2 and EMBS to 3.1. Caspase 3 activation by sulphamoylated compounds in the cervical tumorigenic and estrogen receptor-negative cell lines was demonstrated using a colorimetric assay. Caspase 3 activity in ESE-15-one- and EMBS-treated samples more than doubled when compared to vehicle-treated cells. In another study conducted in our laboratory caspase 3 activity was increased in HeLa cells after exposure to ESE-16. Results obtained from the MDA-MB-231 cell line indicate that all three compounds increase caspase 3 activity with ESE-15-one-treated cells being most affected. Discussion This study focused on investigating the in vitro effects of three novel sulphamoylated 2ME2 analogues on tubulin assembly, microtubule dynamics, cell growth, cell toxicity, caspase activity and cell death induction in a cervical tumorigenic cell line. In addition, the involvement of the intrinsic pathway in HeLa and MDA-MB-231 cells induced by these sulphamoylated compounds was demonstrated by investigating their effects on mitochondrial membrane potential, cytochrome c release and caspase 3 activation. Crystal violet staining showed that ESE-15-one, EMBS and ESE-16 inhibited cell growth significantly where EMBS demonstrated the most potent effect. Research conducted in our laboratory indicated that other analogues of 2ME2 had an inhibitory effect on cell growth in this range in several cell lines including the MCF-7 cell line and esophageal carcinoma SNO cells. Furthermore, the secondgeneration steroid sulphatase inhibitor, STX213, inhibits the proliferation of estrogen dependent positive and estrogen dependent negative breast cancer cells in vitro. Antiproliferative activity induced by 2-methoxyestradiol-bis-sulphamate was detected in the estrogen receptor positive human breast 2883-98-9 custom synthesis adenocarcinoma MCF-7 cell line, prostate cancer cell line, 15325591 tumorigenic estrogen receptor negative breast adenocarcinoma cell line, esophageal carcinoma SNO cells, HeLa and the CAL51 human breast carcinoma cell line. In vivo antiproliferative activity was discovered in xenografts derivative of estrogen receptor positive human breast adenocarcinoma wild type cell line, mitoxantrone resistant breast adenocarcinoma cell line, drug resistant human adenocarcinoma cell line, prostate cancer cell line, MDA-MB-435 and prostate hormone independent PC-3 xenograft model. Pertaining to 2ME2 it was found that 16874052 the sulphamoylated analogues targeted microtubules dynamics, both in vitro and in cells. The in vitro tubulin polymerization assays indicated that sulphamoylated analogues have increased or similar potencies when compared to 2-methoxyestradiol-bis-sulphamate. Ranking of compounds according to tubulin polymerization inhibition potency is as follow: ESE-16 . EMBS .2-methoxyestradiol-bis-sulphamate. Tubulin polymerization assay The antiproliferative effect of 2ME2 has been shown to stem from its ability to inhibit tubulin assembly by interacting at the colchicine site of tubulin. In order to determine if the synthesized compounds may be active 
on cell proliferation through the same mechanism of action, the compounds’ in vitro effects on tubulin polymerization were a