RNA-FISH presented that the fluorescence signal of M2 marker CD206 and miR-15b-5p was enhanced in GC tissues with increased co-localization (Fig. 1C), indicating that the number of M2 macrophages and miR-15b-5p expression were increased in GC, and miR-15b-5p was expressed in M2 macrophages. This evidence concerns the gene MRC1 and gastric cancer.