In sporadically occurring breast cancer, mesenchymal cells have been shown to promote EMT [20,21], but this enhancement of EMT by mesenchymal stromal cells has been shown to be upregulated by BRCA1 PVs, thereby further increasing the metastatic potential of tumours carrying BRCA1 PVs [22,23,24]. This evidence concerns the gene BRCA1 and breast carcinoma.