Increase of IRF-4 expression in BCR/ABL⁺ B lymphoblast cells in response to imatinib treatment. (A) Diagram of MSCV-BCR/ABL-IRES-GFP retroviral construct used to induce B-ALL in mice and transduce E2AGFP pro-B cells. (B) Expression BCR/ABL, IRF-4, and IRF-8 in imatinib-treated or untreated B lymphoblasts derived from BCR/ABL BMT mice suffering from B-ALL, as detected by immunoblotting with an anti-ABL monoclonal antibody (Ab-3; top panel), anti–IRF-4 polyclonal antibody (second panel from top), anti–IRF-8 polyclonal antibody (third panel from top), and anti-dynamin monoclonal antibody (loading control, bottom panel). (C) Expression of BCR/ABL and IRF-4 in imatinib-treated or -untreated BCR/ABL-transformed E2AGFP cells as detected by immunoblotting with antibodies described in panel B.