CXCL8 and malignant colon neoplasm: An in vitro study reveals that the AI-2 signaling molecule elicits inflammatory by inducing IL-8 expression in HCT-8 colon cancer cells (Figure 2).54 Moreover, AI-2 extracted from F. nucleatum promotes macrophage polarization via stimulating the expression of TNFSF9 (Figure 2), which was mainly derived from the tumor microenvironment.71 This result suggests the AI-2 produced by gut microbiota may play a role in the carcinogenesis of CRC through immune cells of the gut.71