KRT18 and gastric cancer: The quantitative analysis showed that the fluorescence intensity of Serpin E1, relative to CK18, was significantly higher in the co-injection groups of GC cells and Serpin E1-overexpressed fibroblasts compared to the co-injection groups of GC cells and control fibroblasts in both subcutaneous and peritoneal tumors (Fig. 5A, B), while no significant difference was observed in DAPI fluorescence intensity between the two corresponding compared groups (Additional file 1: Fig. S4).