To see which molecules from mast cells might have effects on GC cells, we first used some reported molecules (G-CSF, SCF, TGF-β, IL-3, IL-6, IL-17A, IL-22, IL-33) secreted by mast cells to stimulate GC cells, and found that only IL-17A remarkably induced GC cell proliferation (Supplementary Figure 4a). This evidence concerns the gene IL17A and gastric cancer.