When transduced with retroviral vectors encoding the Bcr-Abl kinase, the IL7-dependence of these cells is abrogated, and they initiate acute lymphoblastic leukemia (ALL) when infused intravenously into unconditioned, syngeneic wild type (WT, Arf+/+) recipient mice [2, 4]. The gene discussed is CDKN2A; the disease is acute lymphoblastic leukemia.