To investigate the possible functional role of EFHB and SARAF in breast neoplastic and pre-neoplastic cells, we first analyze the expression of these proteins in the pre-neoplastic breast epithelial MCF10A cell line as well as in the estrogen receptor positive (ER+) breast cancer MCF7 cell line and the triple negative breast cancer (TNBC) cell line MDA-MB-231. The gene discussed is ESR1; the disease is breast cancer.