COL9A1 and gastric cancer: Considering that there were few studies on Collagen family genes in gastric cancer, we performed the bioinformatics analysis of COL1A1, COL2A1, COL3A1, COL4A1, COL5A1, COL6A1, COL7A1, COL8A1, COL9A1, COL10A1, COL11A1 and COL12A1.