These results prompted us to use: i) MSCs as tumoral promoters by co-injecting them in mice together with melanoma cells and ii) ECFCs as carriers of MMP12, which can be recruited within tumors following the chemotactic gradient of SDF1 expressed by MSCs, normally present in tumors, but also able to up-regulate SDF1 expression in tumor cells [35]. The gene discussed is MMP12; the disease is melanoma.