SNAI1 and neoplasm: In order to assess the contribution of cells that have undergone EMT to tumor growth, we co-mixed RFP/luciferase-labeled MCF-7 cells with HMLE-vector, HMLE-Snail, or HMLE-Twist cells, at a 1:1 ratio (0.5 × 106 cells per cell type), and orthotopically implanted these admixtures into female NOD/SCID mice.