PTGR2 and cancer: Since there are abundant cancer-associated fibroblasts (CAFs) in the tumor stromal area under physiological condition, we speculate that under co-culture condition with CAFs, suppressed growth rate or induced cell death we observed in PTGR2-silenced pancreatic cancer cells (BxPC-3 and Capan-2) could be lost because the decrease in 15-keto-PGE2 after silencing of PTGR2 could be provided by the tumor microenvironment.