Notably, we found that intratumoral mast cells expressed significantly higher level of immunosuppressive molecule PD-L1 (Fig. 3a) but not other molecules with immunosuppressive potential such as 2B4, glactin-3, CTLA-4, or ICOSL (Additional file 8: Figure S3a) than that expressed on peritumoral and non-tumor mast cells, indicating a potential role for PD-L1 on mast cells in the GC microenvironment. Here, CTLA4 is linked to neoplasm.