MECOM and myeloid leukemia: In order to establish an in vitro model for human myeloid leukemias constitutively overexpressing EVI1, the human myeloid cell line U937 was infected with a retroviral vector containing the full length human EVI1 cDNA (pBMN_EVI1-IRES-eGFP), or with empty vector (pBMN_IRES-eGFP) as a control.