Effect of anti-IgM on mRNA translation in CLL cells. (A) Signaling-responsive CLL samples (n = 21) were incubated with anti-IgM beads or control beads, or left untreated as a control for 24 hours. mRNA translation was analyzed by quantifying metabolic labeling. (B) As in (A), except cells were pretreated for 1 hour with ibrutinib (n = 5) or tamatinib (n = 4), or dimethyl sulfoxide (DMSO) as a control, before addition of anti-IgM or control beads. The graphs show fold increase in metabolic labeling (means ± standard error of the mean [SEM]) compared with untreated cells (set to 1.0). (C-D) Immunoblot analysis of phosphorylated/total p70S6K and ERK1/2 expression at 30 minutes poststimulation with anti-IgM beads (ibrutinib, n = 6; tamatinib, n = 5). (C) Representative immunoblots. (D) Quantitation of multiple experiments after 30 minutes of stimulation; graphs show normalized p70S6K/ERK1/2 phosphorylation (means ± SEM) as a percentage of control (DMSO) anti–IgM-treated cells. Statistical comparisons between groups are shown (Student t test).