In order to molecularly understand the interaction of oncogenic RAS with cytarabine in AML, we took advantage of mouse bone marrow cells that had been immortalized using a conditional MLL-ENL-ER oncogene [27], [28] and that were co-infected with either an empty vector (control cells) or a vector expressing oncogenic RAS (Ras cells). The gene discussed is MLLT1; the disease is acute myeloid leukemia.