SEC31A-JAK2–derived murine bone marrow transplantation model. (A) Survival curves of 2 independent groups of mice transplanted with SEC31A-JAK2–expressing bone marrow cells show the development of a fatal disease (red and blue curve). Control mice transduced with the empty pMSCV-GFP vector did not show any signs of disease up to 180 days after transplantation. (B) Enlarged lymph nodes of the neck in a mouse presenting with T-lymphoblastic lymphoma. (C) The lymph nodes of mice diagnosed with SEC31A-JAK2–induced T-lymphoblastic lymphoma display effacement of the normal architecture by a monotonous medium-sized blastic proliferation with condensed nuclear chromatin, single nucleolus, and little basophilic cytoplasm (H&E, ×400). Mi indicates mitotic figure. (D) The spleen of mice diagnosed with SEC31A-JAK2–induced T-lymphoblastic lymphoma shows infiltration of mainly CD4⁻/CD8⁺ and CD4⁺/CD8⁺ cells by FACS analysis. (E) The bone marrow of mice presenting with the SEC31A-JAK2–associated myeloid phenotype displays an increased cellularity of the intertrabecular spaces, caused by a hyperplastic myelopoiesis (H&E, ×400). D indicates doughnut cells; Mk, megakaryocyte; G, granulocytes; and BT, bony trabeculae. (F) The bone marrow of mice presenting with the SEC31A-JAK2–associated myeloid phenotype shows an enrichment of gr1⁺/mac1⁺ myeloid cells by FACS analysis. Immunohistochemical images were captured with a Leica DM LB microscope (Leica) using a Leica PL FLUOTAR objective lens (40×/0.70) and a Leica DC200 camera. Images were imported directly into Photoshop CS (Adobe) using the Leica DC200 camera software (Version 2.51).