SNAI1 and breast cancer: Expression of Snail in the lungs of mice orthotopically injected with 4T1 breast cancer cells, compared with healthy control mice, was higher in the endothelial layer of small arteries as soon as 1 week after cancer cell injection and stayed elevated throughout the entire progression of the disease, except for the terminal time point 5 weeks after 4T1 breast cancer cell inoculation (Fig. 4a–g).