PTGER1 and cancer: Further functional studies are needed to confirm these observations.27 Interestingly, highly selective EP2 antagonists (TG4-155 and TG6-10-1) have recently been developed and might therefore be available for pre-clinical studies.28 It is worth noting that different studies have highlighted the importance of PGE2, acting through four GPCRs, PTGER1–4, in the progression of many cancers including colorectal, gastric, lung or breast cancers.29