Altered activation of WNK1-deficient B cells. (A and B) Top: Mean ± SEM levels of the indicated cell surface proteins on control and WNK1-deficient B cells stimulated with anti-IgM (A) or CD40L (B) for the indicated times. Data are shown as MFI normalized to the maximum response of control B cells (set to 100). Bottom: Representative histograms of each surface marker on control and WNK1-deficient B cells stimulated with anti-IgM (A) or CD40L (B) on day 0 and day of the maximum response of control cells. (C) Mean ± SEM concentrations of the indicated cytokines in medium from cultures of control or WNK1-deficient B cells that were unstimulated or stimulated with anti-IgM or CD40L for 72 h. Two-way ANOVA (A and B); Mann–Whitney test (C); asterisks in parentheses next to the names of surface proteins indicate a statistically significant difference between genotypes as determined by two-way ANOVA; asterisks above individual pairs of columns indicate statistically significant differences between genotypes at the indicated time points; *, 0.01 < P < 0.05; **, 0.001 < P < 0.01; ***, 0.0001 < P < 0.001; ****, P < 0.0001. Sample sizes: 5–6 (A); 6 (B); and 9 mutant and 15 control (C). Data are pooled from two (A and B) or three (C) independent experiments.