CCL21 and neoplasm: Although CCL21 can readily be detected within these tumours, few CCR7+ Foxp3+ T cells are found within the tumours compared with a relatively large proportion of CCR7+ Foxp3− T cells.15 Although the implications of these findings are yet to be elucidated, the data certainly argue against CCL21-CCR7 blockade as a means of preventing Treg cell enrichment at least in the carcinogen-induced tumours under study here.