Cloning and Mutagenesis of ER-α Promoter

The human complementary DNA fragment encoding full-length ZEB1^{37 (link)} was prepared by PCR and cloned into pLV-EF1-MCS-IRES-Bsd (Biosettia, San Diego, USA). The lentiviral-based vector pLV-H1-EF1α-puro (Biosettia, San Diego, USA) was used to express shRNAs in breast cancer cells. The human ER-α promoter (-4184/-1951) sequence was obtained by PCR from human genomic DNA and cloned into the pGL3-promoter vector (Promega, Wisconsin, USA). Mutagenesis of E₂-boxes I and II in the human ER-α promoter was performed using a QuikChange Lightning Site-Directed Mutagenesis kit (Stratagene, Santa Clara, USA). Primer sequences are listed in Supplementary Data.