Effects of IL-4 on sIgM expression are mediated via JAK/STAT signaling. CLL samples were treated with IL-4 (0.1-10 ng/mL) for 24 hours and (A) phosphorylated STAT6 (pSTAT6) and (B) sIgM expression analyzed using immunoblotting and flow cytometry, respectively. (A) A representative sample and (B) summarized data (n = 6). (C-D) CLL cells were pretreated with the indicated cytokines and (C) phosphorylated STAT6 (pSTAT6) (n = 9) and (D) sIgM quantified by immunoblotting (n = 9) and flow cytometry (n = 9), respectively. (E) CLL samples (n = 10) were pretreated for 1 hour with the JAK1/3 inhibitor (CP, tofacitinib) or the STAT6 inhibitor (AXON; AS1517499) before IL-4 addition for a further 23 hours. sIgM was quantified by flow cytometry. Graphs show MFI values. Error bars represent the SEM. Statistical significance was determined by a paired Wilcoxon matched pairs signed rank test.