Scientists at Israel’s Weizmann Institute have discovered that whilst the c-Kit gene can promote the early-stage growth of colon cancer cells, its presence later on stops the cancer spreading to other parts of the body. Another oncogene c-Myc has the same duality in breast cancer.
http://wis-wander.weizmann.ac.il/the-double-life-of-a-cancer-gene#.UnX_sVMy1pF