IL-1β released by stromal cells together with other tumor-derived factors, including granulocyte macrophage colony-stimulating factor (GM-CSF), cyclooxygenase 2 (COX-2), IL-6, and VEGF, induce the accumulation and expansion of MDSCs [112, 113] by triggering Janus kinase (JAK)/STAT3 pathways [114]. Here, PTGS2 is linked to neoplasm.