NT5E and gastric cancer: Based on the expression of Ecto-5′-nucleotidase in four human gastric cancer cell lines (AGS, SGC-7901, BGC-823 and NCI-N87), AGS and SGC-7901 cells were chosen for following loss-of-function studies, and the knockdown efficiency of si-Ecto-5′-nucleotidase in AGS and SGC-7901 cells was estimated by Western blot (Figure 4A).