L‐selectin expression is required for appropriate trafficking and tissue distribution of Treg cells under physiological conditions.89 Whereas a majority of Treg cells in tumours are activated and express low levels of L‐selectin, it is possible that L‐selectin+ Treg cells are recruited by tumour HEV, which subsequently down‐regulate L‐selectin expression in response to the activating environment of the tumour. Here, SELL is linked to neoplasm.