The identification of this and other cytokine loops, as for instance the one recently identified in breast cancer and mediated by Granulocyte-macrophage colony-stimulating factor (GM-CSF) and Chemokine (C-C motif) ligand 18 (CCL18)42, opened a new branch of cancer therapies targeting the microenvironment. The gene discussed is CSF2; the disease is breast carcinoma.