Defective B cell development in Zmpste24−/−mice. (A) Decreased bone marrow nucleated cells in Zmpste24−/− mice compared to their wild-type littermates. Data represent mean ± SEM, n ≥5. *P <0.05. (B) Decreased B lymphocytes in Zmpste24−/− mice started from 3 months of age, compared to their wild-type littermates. Data represent mean ± SEM, n = 5. *P <0.05. (C) Representative B cell profile in 5-month-old Zmpste24−/− mice and control, showing decreased pro-B (B220loCD43+) and pre-B (B220loCD43−) cells. (D) Decreased pro-B and pre-B cells in 5-month-old Zmpste24−/− mice. Data represent mean ± SEM, n = 5. *P <0.05. circ. B, circulating B cells; pre-B cells, B cell precursors; pro-B cells, progenitor B cells.