RAG2 and precursor B-cell acute lymphoblastic leukemia: Even so, models like rag2:zjdp2 and rag2:mMyc + rag2:zbcl2 fish provide powerful in vivo templates to discover and pre-clinically test novel agents that circumvent steroid resistance, an important problem not just in T-ALL, but lymphocyte malignancies in general, including B-ALL.