For example, Clostridium difficile metabolically alters the balance of primary and secondary bile acids, which in turn induces the production of C-X-C motif chemokine ligand 16 (CXCL16) in liver sinusoidal endothelial cells, and CXCL16 can induce NK cells to accumulate in the liver and generate anti-tumor immunity (99). Here, CXCL16 is linked to neoplasm.