CD99 and cancer: Notably, we identified several key ligand-receptor pairs in TNChigh cancer cells and immune cells, including NECTIN2-TIGIT, MIF-(CD74+CD44), MDK-NCL, LAMB3-CD44, COL1A2-CD44, COL1A1-CD44, CD99-CD99, APP-CD74, and GZMB-PARD3 were identified in TNChigh cancer cells and immune cells (Fig. 5A).