After a first functional evaluation, indicating specific expression and intracellular compartmentalization for each molecule, we observed that all of them were able to associate with BC cell chromatin and participate in transcriptional transduction of the estrogenic signaling, since their silencing determined deregulation of estrogen-responsive genes and inhibition of ERα-positive BC cell proliferation (Fig. 3A–C). This evidence concerns the gene ESR1 and breast cancer.