In contrast, the growth rate of two independent MT/Shc2F/2F breast tumours was selectively impaired in mice that contain CD8+ T cells (CD8+/+) or retain intact interferon-γ (IFNγ) responses (IFNγ+/+) relative to their immune-deficient (CD8−/− and IFNγ−/−) counterparts. Here, CD8A is linked to breast neoplasm.