SGN-CD19B induces cell cycle arrest. (A) Representative flow cytometry plots for untreated cells (top) and SGN-CD19B-treated cells (bottom). Cells were labeled with BrdU (y-axis) and propidium iodide (x-axis). Gates are indicated with boxes. (B) Cell cycle profile at 48-hour time point. Cells were untreated or incubated with control ADC (10 ng/mL), SGN-CD19B (10 ng/mL), or 0.1 nM PBD. Bar graphs represent results from 3 different experiments. Accumulation of cells in G2/M phase following treatment with SGN-CD19B or free PBD drug (SGD-1882) is statistically significant when compared with untreated and control ADC groups.