Genetic ablation of Arid1a and chemical inhibition of Arid1a–BAF complexes alters B cell IgG1 and IgE CSR frequency. (A) Quantification of Arid1a-WT, Arid1a-HET, and Cre+WT B cells stimulated with anti-CD40⁺IL-4⁺IL-21 frequency to switch to IgG1 and IgE. Combined data from two independent experiments with at least three mice per genotype are shown. (B) Quantification of viability, frequency of plasma cells (CD138⁺, CD19^int), and frequency of IgG1 or IgE surface expression throughout dilution series of chemical lactam. Statistics were generated by one-way ANOVA with Dunnett’s multiple comparison test in A for all comparisons with vehicle alone. Leftmost column is a representative experiment of three independent experiments. **, P < 0.01; ***, P < 0.001; ****, P < 0.0001.