As noted previously [27], mice inoculated with parental 4T1 cells (300,000 cells/mouse) rapidly succumbed to lethal tumor burdens within 7 days (data not shown), while engrafting those that expressed CST-Abl exhibited no overt signs of mammary tumorigenesis and readily survived for 8 weeks, at which point they were euthanized to facilitate the surgical excision of experimental mammary glands. This evidence concerns the gene ABL1 and neoplasm.