c-myc in IgH-c-myc transgenic mice. (A) Schematic representation of the IgH locus (not to scale) with the location of the inserted c-myc. (B) QPCR analysis of c-myc transcripts in B-cell splenocytes (left) and immature bone marrow B-cells (right). B-cell splenocytes results are reported as means ± standard error of the mean (SEM) of 4 c-myc-KIE_μ, 5 c-myc-KIC_μ, 3 c-myc-KIC_α, and 8 wt mice. Immature bone marrow B-cell results are reported as means ± SEM of 5 c-myc-KIE_μ, 3 c-myc-KIC_μ, 4 c-myc-KIC_α, and 3 wt mice. Significances were determined with the Mann-Whitney U test. (C) Western blot analysis of c-myc in B-cell splenocytes from wt and transgenic mice. An experiment with cells from 3 wt mice and 3 c-myc-KIC_μ mice is reported. Significance determined with the Mann-Whitney U test. Please note that line 4 contains a too-diluted c-myc sample not included in the statistical analysis (this line was kept to conserve the original format of the western blot). The original blot is reported in supplemental Figure 1. (D) Proliferation (left) and apoptosis (right) in B splenocytes from IgH c-myc KI transgenic mice. (Left) Proliferation was evaluated with the 3-(4,5 dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl-2-(4-sulfophenyl)-2H-tetrazolium assay after 3 days stimulation with 0.5 μg/mL LPS + 0.1 μg/mL anti-CD40. Results (percentage of increase compared with unstimulated cells) are reported as means ± SEM of 4 c-myc-KIE_μ, 8 c-myc-KIC_μ, 7 c-myc-KIC_α, and 18 wt mice. (Right) Apoptosis in B-cell splenocytes from IgH c-myc KI transgenic mice. Percentages of living cells were determined after 24 hours treatment with 0.01 μM H₂O₂. Results are reported as means ± SEM of 4 c-myc-KIE_μ, 6 c-myc-KIC_μ, 6 c-myc-KIC_α, and 14 wt mice.