CD38 and IRF4 expression in primary MCL cells is correlated with clinical response to bortezomib. (A) Reduction in the ALC on day 21 of one cycle of bortezomib (Bzm) therapy. (B) IRF4 protein expression in leukemic tumor cells from MCL patients assessed by Western blotting and normalized to TBP. Average of 2 independent determinations is shown. Statistical significance was evaluated using the Mann-Whitney nonparametric U test. (C) Mean fluorescence intensity (MFI) of CD38 surface expression was measured on CD19-gated cells using flow cytometry. Statistical significance was evaluated using the Mann-Whitney nonparametric U test. (D) Pearson correlation between IRF4 expression and CD38 surface expression in MCL patients.