The higher number of macrophages and augmented expression of IL-1α and CXC chemokines in highly metastatic tumors versus lower metastatic tumors led us to examine whether IL-1/IL-1R and/or CXC chemokines/CXCR2 were involved in the ability of LNM35 cells to recruit macrophages. The gene discussed is IL1R1; the disease is metastatic neoplasm.