CSL is required for enhanced B-cell proliferation and production of IgG1⁺ cells in the presence of DL1 signals. (A) DNMAML1⁻ and DNMAML1⁺ FO B cells were cultured together at a 1:1 ratio and stimulated as indicated for 72 hours. Results are representative of 3 independent experiments. (B) Histogram presents the fold increase in the number of DNMAML1⁻ or DNMAML1⁺ B cells recovered from OP9-DL1 versus OP9-Ctrl cultures after 72 hours of anti-IgM + anti-CD40 treatment. Error bars represent SEM (n = 3). (C) Histogram presents the fold increase in the frequency of DNMAML1⁻ or DNMAML1⁺ B cells recovered from OP9-DL1 versus OP9-Ctrl cultures after 72 hours of anti-IgM + anti-CD40 treatment. Error bars represent SEM (n = 3).