RNPC3 and B-cell chronic lymphocytic leukemia: In our initial effort to engineer the CLL cell line HG-3 with the SF3B1 mutation using CRISPR Cas9 technology, we observed no successful cases of editing either using Cas9 ribonucleoprotein (RNP) and single-stranded DNA oligo (ssDNA; Supplementary Fig. S3A and S3B) or with Cas9 plasmid and a double-stranded DNA (dsDNA) repair template (Supplementary Fig. S3C and S3D).