COL5A1 and gastric cancer: Compared to normal gastric tissues, 10 core genes, namely, COL1A1, COL1A2, COL3A1, COL5A1, BGN, COL6A3, FN1, COL11A1, COL4A2, and VCAN, were highly expressed in gastric cancer tissues while the expression of GKN1 was significantly decreased.