Ex vivo treatment of primary human T-ALL cells with JAK3 M511I mutation. (A) Western blot analysis of xenograft-derived cells that express JAK3 M511I were cultured ex vivo and treated for 90 minutes with tofacitinib, ruxolitinib, or vehicle (DMSO). (B) Graph shows relative proliferation after 48 hours of treatment with JAK inhibitors of human T-ALL xenograft–derived cells.