TIGIT and cancer: PVR-TIGIT, NECTIN2-TIGIT, and NECTIN3-TIGIT were not expressed in the cancer-free stage, but the obvious cell interaction appeared from stage I, indicating that immunosuppression had already appeared at the beginning of stage I. Additionally, TIGIT ligands are produced by various cell types, including endothelial cells, epithelial cells, fibroblasts, myeloid cells, and pericytes.