PBX1 and acute lymphoblastic leukemia: The authors also used a mouse E2a–PBX1 transgenic B-ALL model and demonstrated that mouse CD19 CAR-T treatment relapses by either causing an alternative splicing of CD19 in B-ALL cells to escape CAR-T cells, or by causing a switch to myeloid leukemias with low Pax5 and Ebf1 expression and increased expression of CD11b and Gr-1 (56).