TIGIT and neoplasm: Fap2 is an adhesin unique to oral Fusobacteria that binds to GalGalNac (a sugar residue overexpressed in tumour tissue) or to the T cell immunoglobulin and ITIM domain (TIGIT) (a receptor of natural killer cells and lymphocytes), inhibiting the cytotoxic function of these cells and promoting a conducive environment for bacteria and tumour cells [9].