As a first approach to this question, we have analysed effects of pharmacological inhibitors and used conditioned media (CM) from wildtype (WT) or Pdia3−/− mouse embryonic fibroblasts (MEFs) on three breast cancer cell lines representing luminal or basal phenotypes, with regard to in vitro properties of cell attachment, spreading and migration that underpin metastatic cell phenotypes in vivo. This evidence concerns the gene PDIA3 and breast carcinoma.