Tumor evolution is stimulated by direct cell–cell contact or by the paracrine secretion by MSCs of cytokines and growth factors such as epidermal growth factor (EGF), interleukin-6 (IL-6), vascular epidermal growth factor (VEGF), insulin-like growth factor 1 (IGF-1), or transforming growth factor beta (TGF-β)23–28. The gene discussed is EGF; the disease is neoplasm.