To rule out that high levels of PGE2 in the TME directly impair T cell function30,50, we knocked out the PGE2 receptors EP2 (encoded by Ptger2) and EP4 (encoded by Ptger4) in OT-1 T cells, followed by their intravenous injection into RTT tumour-bearing mice. Here, PTGER4 is linked to neoplasm.