We previously showed that stable expression of ERβ fused to a TAP tag at either the C-terminus (Ct-ERβ) or N-terminus (Nt-ERβ), suitable for proteomics analyses, causes growth inhibition and re-programming of miRNA expression and the cell proteome in human luminal-like MCF-7 BC cells [25], in line with results obtained in other laboratories [27–29]. Here, ESR2 is linked to breast cancer.