IRF-4/Pip protein and mRNA are expressed in mouse primary macrophages. (A) IRF-4/Pip mRNA is expressed in mouse primary macrophages and B lymphocytes. The expression levels of the IRF-4/Pip gene was determined in primary macrophages and B lymphocytes from wild-type and ICSBP-deficient mice. The arrows show the band for IRF-4/Pip and for the β-actin control. (B) The IRF-4/Pip protein is present in mouse primary macrophages from wild-type and ICSBP-deficient mice. The presence of the IRF-4/Pip protein in mouse macrophages in wild-type and ICSBP−/− mice was determined by a Western blotting assay.