ESR1 and breast carcinoma: These cells are characterized by deficiency in gap-junctional intercellular communication [21], the ability to form budding and ductal organoids on Matrigel [22], the expression of luminal epithelial cell markers (i.e. epithelial membrane antigen and cytokeratin 18) [21], estrogen receptor-alpha (ERα) [23] and the stem cell pluripotency gene Oct-4 [24], similar to the phenotypes of breast carcinoma cells such as the MCF-7 cell line.