This difference in Ki-67 labelling index was cell-autonomous, as tumours resulting from KO/PyMT cells injected into WT C57BL/6 mice had much lower Ki-67 labelling indices than did tumours resulting from injection of WT/PyMT cells into WT C57BL/6 mice (Fig. 3c,d). The gene discussed is MKI67; the disease is neoplasm.