TIGIT and cancer: TIGIT competes with inhibitory receptors KIR2DL5A [4,5] and PVRIG and activating receptor CD226 (DNAM-1) to bind ligands CD155 (PVR) and CD112 (Nectin-2 or PVRL2) which are commonly expressed on cancer cells and antigen-presenting cells (APCs) (reviewed in [6]).