S100A9 and gastrointestinal stromal tumor: Different cell lineages were annotated with typical cell markers as follows: GIST tumor cells (KIT+ and PDGFRA+), epithelial cells (EPCAM+), T cells (CD3D+), NK (natural killer) cells (KLRB1+), B cells (CD79A+), plasma cells (CD38+), macrophages (CD68+), dendritic cells (CD14+), mast cells (TPSAB1+), neutrophils (S100A9+), endothelial cells (PECAM1+), fibroblasts (COL1A1+), and smooth muscle cells (SMC) (ACAT2+) (Figure 1C, S1C).