Plasma-cell differentiation and bortezomib sensitivity. HBL2-PT cells were treated for the times indicated with CpG ODN 2006. (A) Expression of CD19, CD138, and IRF4 was measured by flow cytometry. Triplicates and SD from 3 independent experiments are shown. (B) Detection of λ light chain by sandwich ELISA represented as the ratio between CpG-stimulated and unstimulated cells. Cell death in cells treated with 2.5nM bortezomib for 20 hours in the presence or absence of CpG was measured by flow cytometry using MitoTracker, and is shown as the ratio between CpG-stimulated and unstimulated cells. A representative experiment of 3 is shown. (C) Induction of ER-resident chaperones assessed by Western blotting in RIPA lysates using γ-tubulin for loading normalization. Densitometry measurements are given for the ratio between CpG-stimulated and unstimulated cells.