IL6 and neoplasm: For instance, prostaglandin E2, cyclooxygenase 2, IL-6, colony stimulating factor and VEGF were found to induce the differentiation of CD11b+GR1+ MDSCs from bone marrow stem cells of mice, whereas COX-2 inhibitors or IL-1 deficient mice delayed tumor progression suggesting partial mediation of MDSCs by PGE2 and/or IL-1 [9,11,13].