COL1A1 and gastric cancer: Correlation analysis of MMD with six important markers of gastric cancer-related fibroblasts (CAFs), including collagen type I alpha 1 chain (COL1A1), collagen type I alpha 2 chain (COL1A2), collagen type III alpha 1 chain (COL3A1), collagen type V alpha 1 chain (COL5A1), fibronectin 1 (FN1), and secreted protein acidic and cysteine rich (SPARC), was carried out.