In hepatocellular carcinoma, the gut microbiome uses bile acids as messengers to regulate chemokine CXCL16 levels on liver sinusoidal endothelial cells in order to control the accumulation of CXCR6+ hepatic natural killer T (NKT) cells that keep liver tumors at bay [24]. Here, CXCL16 is linked to hepatocellular carcinoma.