Effect of boric acid in bortezomib-induced apoptosis. DoHH2 (A) or CLL (B,C) cells were pretreated in various concentrations of boric acid for 2 hours and then treated with 20 nM of bortezomib with or without 20 μM of quercetin for 16 hours. Cells were suspended in the culture medium (A,B) or 50% autologous plasma (C). BA indicates boric acid; Q, quercetin; B, bortezomib. Data shown (mean ± SD) were from 5 separate experiments; error bars have been omitted for clarity.