PTGS2 and gastric cancer: Remarkably, nuclear β-catenin levels were closely related with COX2 expression, since high levels of the protein were observed in MKN45, AGS, SNU16 and KATOIII cells, compared with N87, SNU1 and WI38 cells (Figure 1B), implying a role for Wnt signaling in COX2 mRNA expression in GC cells.