Figure 2.

Co‐stimulatory, co‐inhibitory and cytokine receptors expressed by regulatory T (Treg) cells in tumours. Co‐stimulatory (left) and co‐inhibitory (middle) molecules, as well as cytokine receptors (right), deliver signals to Treg cells following engagement by their ligands expressed by immune and/or non‐immune cell types within the tumour. Positive and negative signs in the Treg cell indicate either a positive effect on proliferation (Prolif.) or function (Funct.) or an inhibitory effect (i.e. reduced function), respectively, after receptor engagement. Question marks (?) indicate that the outcome of the receptor engagement in the Treg cell warrants further investigation.