We observe that tumour cell-derived granulocyte–MØ colony-stimulating factor (GM-CSF) induces expression of Oncostatin M (OSM) in MØs, which in turn induces expression and secretion of pro-tumourigenic inflammatory mediators, such as IL6 family members (e.g. IL6 and LIF) and CXC- and CC- chemokines (CXCL1, CCL2 and CCL7), in stromal fibroblasts. The gene discussed is CCL2; the disease is neoplasm.