Our observation of an association between a more invasive phenotype and the shift to cytoplasmic expression of SnON in MCF-7 when co-cultured with MSCs is interesting in light of increased cytoplasmic SnON associated with poor prognostic features in ductal breast cancer including higher Ki67 expression and loss of ER/PR [45], the latter usually associated with an invasive phenotype. Here, ESR1 is linked to breast carcinoma.