Fig. 4
From: Cancer immunotherapy: the beginning of the end of cancer?
T cell activation in the tumor milieu. a Programmed cell death protein 1 (PD1) receptor is an inhibitory receptor expressed by antigen-stimulated T cells. Interactions between PD1 and its ligand, PD-L1, expressed in many tumors activate signaling pathways that inhibit T-cell activity and thus block the antitumor immune response. b Antibodies targeting PD1 or PD-L1 block the PD1 pathway and reactivate T cell activity. MCH, Major histocompatibility complex; TCR, T cell receptor. (Adapted from [77])