Down regulation of GKN1 in gastric cancer cell lines and gastric tissue specimens. GKN1 RNA and protein were extracted from tumor cell lines and gastric tissue samples and then subjected to RT-PCR and Western blotting analysis. A: GKN1 expression in gastric cancer cell lines. GKN1 mRNA and protein were absent in the cell lines except for mRNA was weakly expressed in MKN28 cells. Normal gastric mucosa (N) was also detected as control group. B: GKN1 expression in gastric tissue specimens. Expression of GKN1 mRNA and protein were significant down-regulated or even absent in gastric cancer tissues but abundant in the corresponding distant non-cancerous tissues (CDNT).