PTGS2 and gastric cancer: We initially determined the expression levels of COX2 mRNA in human GC cell-lines MKN45, N87, SNU1, SNU16, KATOIII and AGS [40], [41], [42], as well as WI38 fibroblasts used here as a control cell line [43], examining whether they were correlated with Wnt/β-catenin signaling.