The second kind of signals includes inflammatory cytokines and chemokines, produced mostly by the tumor stroma, such as IFN-γ, IL-4, IL-6, IL-1β, and CXCL1, which are responsible of inducing the suppressive activity of MDSCs via NF-κB, STAT1, and STAT6 (10, 15). The gene discussed is CXCL1; the disease is neoplasm.