When CD8+ T cells from spleens of 4T1 breast tumour-bearing mice were transfected with miR-149-3p mimic for 48 h, the level of miR-149-3p in CD8+ T cells was upregulated after miR-149-3p mimic transfection (electronic supplementary material, figure S2). This evidence concerns the gene CD8A and breast neoplasm.