Reduced essential factors required for B lymphopoiesis owing to defective NF-κB signaling in Zmpste24−/−bone marrow stromal cells. (A) Representative blots showing cytokine expression in wild-type and Zmpste24−/− bone marrow stromal cells (BMSCs). Corresponding cytokines showed significant difference in (B) were labeled with number. (B) Downregulated cytokines in Zmpste24−/− BMSCs and most of them (#) are under transcriptional control of NF-κB, especially those required for early B cell development, including Vcam-1, SDF-1α, Flt3L and TSLP. Data represent mean ± SEM, n = 3. P <0.05, Zmpste24−/− BMSCs versus wild-type. POS, positive control (GAPDH); NEG, negative control (Blank).