Surface expression of IL-7 receptors on B cells from C/EBPβ+/+ or C/EBPβ−/− mice. B lymphocytes obtained from long-term cultures of BM stromal cells were stained with B220-FITC MoAb and with IL-7 biotin, followed by incubation with streptavidin-PE. 31.5% and 34.7% of cells expressed IL-7 receptors in the case of C/EBPβ+/+ or C/EBPβ−/− mice, respectively. Similar results were obtained in the case of BM B-cell subpopulations (not shown).