ID4 expression in B cells from Eμ-TCL1 transgenic mice. (A) Quantitative ID4 expression in wild-type (WT) and Eμ-TCL1 transgenic mouse spleen cells by real-time RT-PCR. The expression in Eμ-TCL1-tg mouse samples is shown relative to the expression in WT cells (defined as 1). Error bars indicate SD. *Indicates statistically significant differences based on 2-sample t tests. (B) ID4 methylation in WT and Eμ-TCL1-tg mouse spleen cells at different time points as measured by quantitative MassARRAY based methylation analysis. Gray indicates unavailable data. The diagram above it depicts the relative location of the amplicon with respect to exon 1 and exon 2 of ID4. The bar at the bottom indicates the color coding for the DNA methylation levels (yellow, 0% methylation; dark purple, 100% methylation).