IRF4,8 induce the expression of Ikaros and Aiolos in pre-B cells. (A) Expression of Ikaros and Aiolos is defective in IRF4,8^−/− pre-B cells. Bone marrow cells were isolated from IRF4,8^−/− and wild-type control mice. Cells were stained with antibodies against B220, CD43, IgM, and the pre-B cells (B220⁺, CD43^low/−, and IgM⁻) were isolated by sorting. The relative expression of Ikaros and Aiolos was measured in wild-type and IRF4,8^−/− pre-B cells by real-time PCR. The values in the control pre-B cells were arbitrarily set as 1. (B,C) Total RNA isolated from ER-, IRF4ER-, and IRF8ER-infected cells described in Figure 1C and D were subjected to real-time analysis to measure the expression of Ikaros (Figure 1C) and Aiolos (Figure 1D). The values are average and SD of 3 independent experiments.