In mice bearing similar tumour volumes, we found a significant increase in distant luminescence signal of MCF7-Ctrl-luc (non-EMT) cells when they were co-injected with MCF7-Six1 (EMT) cells compared to when ‘singly' injected (Fig. 6b,c), indicating that Six1 is able to non-cell autonomously increase the metastasis of non-Six1 cells in vivo. The gene discussed is SIX1; the disease is neoplasm.