ESR1 and breast carcinoma: MCF10DCIS.com cells are estrogen receptor (ER)-negative premalignant mammary carcinoma cells derived from the ‘normal’ MCF10A cell line and are known to form well-defined comedo-like DCIS structures when injected as subcutaneous or intraductal xenografts (Behbod et al., 2009; Miller et al., 2000).