These data lead us to propose a scheme in which metastatic breast cancer cells can stimulate their microenvironment and in particular MSCs, to produce IL-1β and presumably other undefined factors, activate the NF-κB pathway and stimulate the production of chemokines by MSCs, which in turn will increase the aggressiveness of the breast cancer cells (Figure 6). Here, NFKB1 is linked to breast carcinoma.