CRISPR/Cas9 targeting of immunoglobulin genes eliminates BCR surface expression and reduces proliferation of GCB-DLBCL lines. (A) Surface levels of IgM and Igκ of OCI-Ly19 cells, measured by flow cytometry (FCM) 5 days after electroporation with a Cas9/gRNA plasmid targeting their IgH HVR. (B) Histogram of IgM surface levels in OCI-Ly19 cells over time (D = days after electroporation), indicating the proportion and BCR surface level of BCR-KO cells (*). (C) Proportion over time of BCR-KO cells (made by IgH targeting) in DLBCL lines, normalized to the initial value determined 3 days after electroporation. Cell lines with names in black express IgM; those in red, an IgG isotype. (D) Absolute growth curves for BCR-replete and BCR-KO cells of representative GCB-DLBCL lines, relative to the starting point 3 days after electroporation. Panels C and D display the mean of results from 3 biological replicates, each using a different IgH-targeting gRNA, with error bars showing ± standard deviation (SD).