CD19 and B-cell chronic lymphocytic leukemia: In detail, they crossed the murine CLL line CD19cre/+Mdrfl/+Sf3b1 K700Efl/+ with a mouse strain that conditionally expresses Cas9 to obtain a donor mouse line Cd19-Crefl/+Sf3b1fl/+ Mdrfl/+Cas9fl/+.