PDCD1 and neoplasm: The expression of stimulatory and inhibitory coreceptors of T cells, including 4-1BB, PD-1, TIGIT and Lag3, was also enhanced in these tumor-infiltrating CD8+ T cells by treatment with the SCD1 inhibitor, suggesting the activation and subsequent exhaustion of tumor antigen-specific T cells in tumors (figure 2B, online supplemental figure 3A right panel).