In the tumor microenvironment, ω6-PUFAs can up-regulate the production of PGE2 colorectal cancer cells and promote the transformation of myeloid inhibitory cells (MDSC) into M2 macrophages [165]; hypoxia-inducible factor-1 secreted by M2 macrophages α (HIF-1 α) promote tumor invasion and metastasis by inducing the expression of COX-2 and PGE2 in stromal cells and tumor tissues [166]. Here, PTGS2 is linked to neoplasm.