MPAL: mixed phenotype acute leukemia; MPO: myeloperoxidase; CMYC: c-MYC (a proto-oncogene protein; assessed for overexpression via immunohistochemistry); BCL: BCL-2 and BCL-6 (B-cell lymphoma 2 and B-cell lymphoma 6 proteins, respectively; both assessed via immunohistochemistry); MUM1: multiple myeloma oncogene-1; PAX5: paired box 5; EBER: Epstein-Barr virus-encoded RNA (detected via fluorescence in situ hybridization (FISH)). Here, IRF4 is linked to acute leukemia.