ESR1 and breast cancer: We generated CHi-C libraries in two ER+ breast cancer cell lines (T-47D, ZR-75-1), two ER− breast cancer cell lines (BT-20, MDA-MB-231), one “normal” breast epithelial cell line (Bre80-Q-TERT (Bre80)) and a control, non-breast lymphoblastoid cell line (GM06990) (Supplementary Fig. 1).