Defective early B lymphopoiesis in Zmpste24−/−mice is cell-extrinsic. (A) Representative plots showing B cell profile (pro- and pre-B) analyses in recipients with Zmpste24−/− or Zmpste24+/+ donor cells. (B) Detailed B cell profile analyses, including the number of pro-B cells, pre-B cells and circ. B cells, showed a complete rescue of defective early B cell development in Zmpste24−/− mice. Data represent mean ± SEM, n = 4. circ. B, circulating B cells; pre-B cells, B cell precursors; pro-B cells, progenitor B cells.