FASLG and neoplasm: There are two main obstacles to this pathway57: 1) tumor cell Fas transcriptional downregulation or deletion, Fas/FasL pathway-mediated apoptosis of tumor cells weakens or disappears; 2) T cells express Fas molecules on the surface, while some tumor cells express FasL, attacking T cells in reverse, causing T cell apoptosis, further increasing the risk of immune escape.