In a second experiment, where the input ratio of WT : CXCR3−/− CD4+ T cells was 1·2 : 1, we again saw a trend for an increase in the proportion of WT cells in the spleen, draining and non-draining lymph nodes relative to the input population (1·3 : 1, 2 : 1 and 2 : 1, respectively) but a small increase in CXCR3−/− CD4+ T cells in the tumour (0·9 : 1). This evidence concerns the gene CXCR3 and neoplasm.