Fig. 1From: Tracers for non-invasive radionuclide imaging of immune checkpoint expression in cancerImmune checkpoint expression and main interactions on cell types which predominantly express them. Depicted are immune checkpoints for which tracers have been developed. Not all immune checkpoint interactions are known nor are all interactions displayed. For further reading on immune checkpoints, we refer to De Sousa Linhares et al. (2018) PD-L1: Programmed Death-ligand 1, PD-1: Programmed death-1, CTLA-4: Cytotoxic T lymphocyte associated antigen-4, A2aR: Adenosine 2a receptor, IDO: Indoleamine 2,3-dioxygenaseBack to article page