ESR1 and breast cancer: This fusion was stably expressed in MCF7 (ER+) and MDA-MB-231 (ER-) breast cancer cell lines [MCF7-mHIF-YFP-DD and 231-mHIF-YFP-DD] and inducible expression was verified by Western blot for HIF1-alpha performed on nuclear extracts following 48 h of culture with 10 μM TMP (Fig. 1b, Additional file 1: Figure S1 shows an unedited blot).