Dox is often enriched in the cytoplasm in ABC-DLBCL cell lines. (A) Subcellular distribution of Dox in representative GCB (Val) and ABC (Ly3) cell lines, as assessed by confocal microscopy after treating cells with IC₅₀ concentrations of Dox for 24 hours. Scale bar, 10 μM. Quantification of the confocal microscopy data from 4 GCB and 5 ABC cell lines is summarized in (B). Error bars indicate SD from measurements of multiple cells (see supplemental Methods for details). Dotted horizontal line marks the 50% level of nuclear Dox enrichment.