ETV6 and acute lymphoblastic leukemia: The infection of primary blasts isolated from the bone marrow of pre-B ALL patients with a lentiviral vector expressing miR-181a increased the level of miR-181a by an average of 2.5-fold (range from 1.5- to 3-fold) in three ETV6/RUNX1-positive samples compared with the controls (Fig 5C).