PTGS1 and neoplasm: Quantification of TIL populations across PGE2-deficient Ptgs1/Ptgs2−/− BRAFV600E tumours from WT mice and PGE2-producing control BRAFV600E from WT mice, Ptger2−/−Ptger4fl/fl mice and Cd4crePtger2−/−Ptger4fl/fl mice (Extended Data Fig. 7a–c) revealed that the numbers of TCF1+ TILs were comparable among all groups (Extended Data Fig. 7b).