Increased Bak expression was observed in patient samples following bortezomib treatment. (A) A visible increase in Bak expression was observed in 3 of 10 primary B-NHL patient samples treated ex vivo with bortezomib (5-10nM). This visible increase in Bak expression correlated with a fold change in Bak of ≥ 1.5-fold. Individual fold change values were normalized to Actin and are indicated next to Bak Western blots. (B) Seven of 10 patient samples treated ex vivo with bortezomib had no visible change in Bak expression. (C) Following the general pattern established by sensitive and resistant cells, primary B-NHL cells that demonstrated no induction of Bak (ΔBak < 1.5-fold) following bortezomib treatment died more rapidly than those in which Bak increased (ΔBak ≥ 1.5-fold). B-NHL cells derived from patient 11 did not follow this general pattern. No pattern of sensitivity to rituximab (D) or adriamycin (E) was noted when the same 10 patient samples were segregated based on the ability of bortezomib to induce Bak expression.