ESR2 and colon adenocarcinoma: Therefore, the aim of this study was to evaluate the role of natural δ-Toc and two of its semi-synthetic derivatives, bis-δ-tocopheryl sulfide (δ-Toc)2S and bis-δ-tocopheryl disulfide (δ-Toc)2S2, on ERβ-mediated cell proliferation and the regulation of ERβ expression in human colon adenocarcinoma HCT8 cells transfected with the plasmid vector pCXN2-hERβ for the overexpression of ERβ (HCT8-β8).