PTGER4 and gastric cancer: A number of genetic loci for gastric cancer susceptibility—such as MUC1 rs4072037, ZBTB20 rs9841504, PSCA rs2294008, PLCE1 rs2274223, and PTGER4 and PRKAA1 rs13361707—were recently discovered by GWAS.[19–21] In order to avoid false-positive results, a large number of confirmation studies and meta-analyses followed.[22, 23, 25, 32, 33] However, the results have not always been consistent.