(A) Flow cytometry analysis of B cell development in bone marrow from wild-type (WT) and Mb1-cre ABCB7 cKO mice in the presence or absence of a fully rearranged transgenic BCR specific for hen egg lysozyme (HEL-Ig). B cell populations were identified by gating on B220+ CD19+ cells: pro-B cells (CD43+), BP-1+ pro-B cells, and Fr. E/F cells (CD43-/low IgM+). Contour plots are representative of seven independent experiments (total of 9–13 mice/group). (B) Graphs showing CD19+ absolute cell numbers (left) and percentage of live cells (right) in the bone marrow of mice analyzed in (A). (C) Flow cytometry analysis of splenic CD19+ cells in mice from (A). Contour plots are representative of seven independent experiments (total of 9–13 mice/group). (D) Graph showing absolute cell numbers of CD19+ cells in the spleen of mice analyzed in (C). (E) Flow cytometry analysis of Phen Green SK fluorescence quenching by heavy metal ions in bone marrow and splenic CD19+ cells from WT and Mb1-cre ABCB7 cKO mice. Indicated values are the proportion of cells with quenched fluorescence, and quantification is shown on the right. Offset histograms are representative of three independent experiments (total of 3–5 mice/group). (B, D, E) Error bars represent SEM, and p-values are indicated above the data. Statistics were obtained by using an unpaired Student’s t-test.