Figure 4. IL‐21 synergizes with BCR and CD40 to promote AKT and S6 phosphorylation.

• A–E
  Phosphoflow analysis of naïve WT or Il21r ^−/− B cells following in vitro culture for 3 h with or without IL‐21 (20 ng/ml) and/or in the presence of BCR cross‐linking (biotinylated anti‐Igκ + anti‐Igλ and avidin‐mediated cross‐linking) or agonistic anti‐CD40. (A) Exemplary p‐AKT (S473) staining and (B) quantification of p‐AKT median fluorescence intensity (MedFI). (C) Exemplary p‐S6 (Ser235/236) staining and (D) quantification of frequency of p‐S6‐positive cells and (E) p‐S6 median fluorescence intensity (MedFI) of p‐S6‐positive cells.
• F, G
  In vitro cell culture of CTV labeled SW_HEL B cells with or without IL‐21 (20 ng/ml) and anti‐CD40 for 3 days and analysis by flow cytometry. (F) Exemplary CTV division peaks. (G) Quantification of the proportion SW_HEL B that had divided and thus diluted CTV.

Data information: Data are representative of 4 biological replicates (n = 4). Statistical analysis by one‐way ANOVA with Tukey's post‐test (D), t‐test (B, E) or two‐way ANOVA with correction for multiple comparisons using Šidák method (G). *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001; ****P ≤ 0.0001.