Furthermore, MCF7 cells grown in the PDSs of this more aggressive subgroup (SOM1) expressed higher levels of VIM and SNAI2. These well-known cancer associated proteins and regulators are linked to epithelial-mesenchymal transition which is mediating metastasis formation and a more aggressive cell phenotype [23], supporting the finding that patients belonging to this subgroup have a more aggressive tumor microenvironment affecting both cancer cell secretion and gene expression. This evidence concerns the gene SNAI2 and neoplasm.