PTGS2 and esophageal squamous cell carcinoma: Unsurprisingly, in mice ESCC, comparing with non-tumor tissue, several key metabolic genes in arachidonic acid metabolism (Ptgs2, Cyp4a10, Cyp2b10, Hpgds and Alox8) were up-regulated in tumor tissues and M2 macrophages marker Arg1 was also increased in tumor tissues (Figure 6A), indicating a correlation between arachidonic acid metabolism and M2-TAMs formation.